From 971a8c8481abbb255acb9136255f6ffca05cff0e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Tue, 22 Jul 2025 16:49:27 +0200
Subject: [PATCH 01/10] chore: improve errors in iterators.R

---
 R/iterators.R                      | 50 ++++++++++++------------------
 tests/testthat/_snaps/iterators.md | 18 ++++++++++-
 tests/testthat/test-iterators.R    | 16 ++++++++++
 3 files changed, 52 insertions(+), 32 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index 31e87dbe307..625a2e99f3e 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1079,7 +1079,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
       }
       if (is.logical(ii) && (length(ii) != length(x) && length(ii) != 1)) {
         cli::cli_abort(
-          "Error: Logical index length does not match the number of edges. Recycling is not allowed."
+          "Logical index length does not match the number of edges. Recycling is not allowed."
         )
       }
 
@@ -1144,14 +1144,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @name igraph-vs-attributes
 #' @export
 `[[<-.igraph.vs` <- function(x, i, value) {
-  if (
-    !"name" %in% names(attributes(value)) ||
-      !"value" %in% names(attributes(value))
-  ) {
-    cli::cli_abort("Invalid indexing.")
+  if (!rlang::has_name(attributes(value), "name")) {
+    cli::cli_abort("Can't find {.val name} for attribute.")
   }
   if (is.null(get_vs_graph(x))) {
-    stop("Graph is unknown.")
+    cli::cli_abort("Can't find graph.")
   }
   value
 }
@@ -1166,14 +1163,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @name igraph-es-attributes
 #' @export
 `[[<-.igraph.es` <- function(x, i, value) {
-  if (
-    !"name" %in% names(attributes(value)) ||
-      !"value" %in% names(attributes(value))
-  ) {
-    stop("Invalid indexing.")
+  if (!rlang::has_name(attributes(value), "name")) {
+    cli::cli_abort("Can't find {.val name} for attribute.")
   }
   if (is.null(get_es_graph(x))) {
-    stop("Graph is unknown.")
+    cli::cli_abort("Can't find graph.")
   }
   value
 }
@@ -1239,7 +1233,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 `$.igraph.vs` <- function(x, name) {
   graph <- get_vs_graph(x)
   if (is.null(graph)) {
-    cli::cli_abort("Graph is unknown")
+    cli::cli_abort("Can't find graph.")
   }
   res <- vertex_attr(graph, name, x)
   if (is_single_index(x)) {
@@ -1292,7 +1286,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 `$.igraph.es` <- function(x, name) {
   graph <- get_es_graph(x)
   if (is.null(graph)) {
-    cli::cli_abort("Graph is unknown")
+    cli::cli_abort("Can't find graph.")
   }
   res <- edge_attr(graph, name, x)
   if (is_single_index(x)) {
@@ -1310,7 +1304,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @export
 `$<-.igraph.vs` <- function(x, name, value) {
   if (is.null(get_vs_graph(x))) {
-    cli::cli_abort("Graph is unknown")
+    cli::cli_abort("Can't find graph.")
   }
   attr(x, "name") <- name
   attr(x, "value") <- value
@@ -1325,7 +1319,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @family vertex and edge sequences
 `$<-.igraph.es` <- function(x, name, value) {
   if (is.null(get_es_graph(x))) {
-    cli::cli_abort("Graph is unknown")
+    cli::cli_abort("Can't find graph.")
   }
   attr(x, "name") <- name
   attr(x, "value") <- value
@@ -1336,11 +1330,8 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @export
 `V<-` <- function(x, value) {
   ensure_igraph(x)
-  if (
-    !"name" %in% names(attributes(value)) ||
-      !"value" %in% names(attributes(value))
-  ) {
-    cli::cli_abort("invalid indexing")
+  if (!rlang::has_name(attributes(value), "name")) {
+    cli::cli_abort("Can't find {.val name} for vertex attribute.")
   }
   i_set_vertex_attr(
     x,
@@ -1360,11 +1351,8 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @export
 `E<-` <- function(x, path = NULL, P = NULL, directed = NULL, value) {
   ensure_igraph(x)
-  if (
-    !"name" %in% names(attributes(value)) ||
-      !"value" %in% names(attributes(value))
-  ) {
-    cli::cli_abort("invalid indexing")
+  if (!rlang::has_name(attributes(value), "name")) {
+    cli::cli_abort("Can't find {.val name} for edge attribute.")
   }
   i_set_edge_attr(
     x,
@@ -1563,7 +1551,7 @@ as_igraph_vs <- function(graph, v, na.ok = FALSE) {
   if (is.character(v) && "name" %in% vertex_attr_names(graph)) {
     v <- as.numeric(match(v, V(graph)$name))
     if (!na.ok && any(is.na(v))) {
-      cli::cli_abort("Invalid vertex names")
+      cli::cli_abort("Invalid vertex names {.arg v}.")
     }
     v
   } else {
@@ -1575,7 +1563,7 @@ as_igraph_vs <- function(graph, v, na.ok = FALSE) {
       res <- as.numeric(v)
     }
     if (!na.ok && any(is.na(res))) {
-      cli::cli_abort("Invalid vertex name(s)")
+      cli::cli_abort("Invalid vertex name(s) {.arg v}.")
     }
     res
   }
@@ -1618,7 +1606,7 @@ as_igraph_es <- function(graph, e) {
     res <- as.numeric(e)
   }
   if (any(is.na(res))) {
-    cli::cli_abort("Invalid edge names")
+    cli::cli_abort("Invalid edge names {.arg e}.")
   }
   res
 }
@@ -1638,7 +1626,7 @@ parse_op_args <- function(..., what, is_fun, as_fun, check_graph = TRUE) {
   args <- list(...)
 
   if (any(!sapply(args, is_fun))) {
-    cli::cli_abort("Not {what} sequence")
+    cli::cli_abort("Not {what} sequence.")
   }
 
   ## get the ids of all graphs
diff --git a/tests/testthat/_snaps/iterators.md b/tests/testthat/_snaps/iterators.md
index d01392169aa..e0d56cc988c 100644
--- a/tests/testthat/_snaps/iterators.md
+++ b/tests/testthat/_snaps/iterators.md
@@ -106,5 +106,21 @@
       E(g)[c(TRUE, FALSE)]
     Condition
       Error in `FUN()`:
-      ! Error: Logical index length does not match the number of edges. Recycling is not allowed.
+      ! Logical index length does not match the number of edges. Recycling is not allowed.
+
+# `[[<-.igraph.es` and `V<-` error well
+
+    Code
+      V(g) <- "blue"
+    Condition
+      Error in `V<-`:
+      ! Can't find "name" for vertex attribute.
+
+---
+
+    Code
+      E(g)[1] <- "blue"
+    Condition
+      Error in `[<-`:
+      ! Can't find "name" for attribute.
 
diff --git a/tests/testthat/test-iterators.R b/tests/testthat/test-iterators.R
index 50790e1623a..4e885bb01be 100644
--- a/tests/testthat/test-iterators.R
+++ b/tests/testthat/test-iterators.R
@@ -447,3 +447,19 @@ test_that("logical indices are not recycled", {
   expect_snapshot(V(g)[c(TRUE, FALSE)], error = TRUE)
   expect_snapshot(E(g)[c(TRUE, FALSE)], error = TRUE)
 })
+
+test_that("`[[<-.igraph.es` and `V<-` error well", {
+  g <- make_(
+    ring(10),
+    with_vertex_(
+      name = LETTERS[1:10],
+      color = sample(1:2, 10, replace = TRUE)
+    )
+  )
+  expect_snapshot(error = TRUE, {
+    V(g) <- "blue"
+  })
+  expect_snapshot(error = TRUE, {
+    E(g)[1] <- "blue"
+  })
+})

From 2be846a1326ce77879e845115ea2c049b705ec00 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 12 Aug 2026 16:11:23 +0200
Subject: [PATCH 02/10] tests thx Claude

---
 R/iterators.R                      |  20 ++++++
 tests/testthat/_snaps/iterators.md | 100 ++++++++++++++++++++++++++++-
 tests/testthat/test-iterators.R    |  97 +++++++++++++++++++++++++++-
 3 files changed, 215 insertions(+), 2 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index c443860a302..5b9983b5f68 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1200,6 +1200,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (!rlang::has_name(attributes(value), "name")) {
     cli::cli_abort("Can't find {.val name} for attribute.")
   }
+  if (!rlang::has_name(attributes(value), "value")) {
+    cli::cli_abort(
+      "Can't find {.val value} for attribute. To remove an attribute, use {.fn delete_vertex_attr} instead."
+    )
+  }
   if (is.null(get_vs_graph(x))) {
     cli::cli_abort("Graph is unknown.", .internal = TRUE)
   }
@@ -1219,6 +1224,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (!rlang::has_name(attributes(value), "name")) {
     cli::cli_abort("Can't find {.val name} for attribute.")
   }
+  if (!rlang::has_name(attributes(value), "value")) {
+    cli::cli_abort(
+      "Can't find {.val value} for attribute. To remove an attribute, use {.fn delete_edge_attr} instead."
+    )
+  }
   if (is.null(get_es_graph(x))) {
     cli::cli_abort("Graph is unknown.", .internal = TRUE)
   }
@@ -1386,6 +1396,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (!rlang::has_name(attributes(value), "name")) {
     cli::cli_abort("Can't find {.val name} for vertex attribute.")
   }
+  if (!rlang::has_name(attributes(value), "value")) {
+    cli::cli_abort(
+      "Can't find {.val value} for vertex attribute. To remove an attribute, use {.fn delete_vertex_attr} instead."
+    )
+  }
   i_set_vertex_attr(
     x,
     attr(value, "name"),
@@ -1407,6 +1422,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (!rlang::has_name(attributes(value), "name")) {
     cli::cli_abort("Can't find {.val name} for edge attribute.")
   }
+  if (!rlang::has_name(attributes(value), "value")) {
+    cli::cli_abort(
+      "Can't find {.val value} for edge attribute. To remove an attribute, use {.fn delete_edge_attr} instead."
+    )
+  }
   i_set_edge_attr(
     x,
     attr(value, "name"),
diff --git a/tests/testthat/_snaps/iterators.md b/tests/testthat/_snaps/iterators.md
index e0d56cc988c..608b22d090f 100644
--- a/tests/testthat/_snaps/iterators.md
+++ b/tests/testthat/_snaps/iterators.md
@@ -108,7 +108,31 @@
       Error in `FUN()`:
       ! Logical index length does not match the number of edges. Recycling is not allowed.
 
-# `[[<-.igraph.es` and `V<-` error well
+# assigning `NULL` errors clearly instead of silently doing nothing
+
+    Code
+      V(g)$color <- NULL
+    Condition
+      Error in `V<-`:
+      ! Can't find "value" for vertex attribute. To remove an attribute, use `delete_vertex_attr()` instead.
+
+---
+
+    Code
+      V(g)[1:3]$color <- NULL
+    Condition
+      Error in `[<-`:
+      ! Can't find "value" for attribute. To remove an attribute, use `delete_vertex_attr()` instead.
+
+---
+
+    Code
+      E(g)$weight <- NULL
+    Condition
+      Error in `E<-`:
+      ! Can't find "value" for edge attribute. To remove an attribute, use `delete_edge_attr()` instead.
+
+# direct misuse of `V<-`/`E<-`/`[<-`/`[[<-` errors well
 
     Code
       V(g) <- "blue"
@@ -116,6 +140,22 @@
       Error in `V<-`:
       ! Can't find "name" for vertex attribute.
 
+---
+
+    Code
+      E(g) <- "blue"
+    Condition
+      Error in `E<-`:
+      ! Can't find "name" for edge attribute.
+
+---
+
+    Code
+      V(g)[1] <- "blue"
+    Condition
+      Error in `[<-`:
+      ! Can't find "name" for attribute.
+
 ---
 
     Code
@@ -124,3 +164,61 @@
       Error in `[<-`:
       ! Can't find "name" for attribute.
 
+---
+
+    Code
+      V(g)[[1]] <- "blue"
+    Condition
+      Error in `[[<-`:
+      ! Can't find "name" for attribute.
+
+---
+
+    Code
+      E(g)[[1]] <- "blue"
+    Condition
+      Error in `[[<-`:
+      ! Can't find "name" for attribute.
+
+# querying or setting attributes errors when the graph is unknown
+
+    Code
+      vs$color
+    Condition
+      Error in `vs$color`:
+      ! Can't find graph.
+
+---
+
+    Code
+      vs$color <- "blue"
+    Condition
+      Error in `$<-`:
+      ! Can't find graph.
+
+---
+
+    Code
+      es$weight
+    Condition
+      Error in `es$weight`:
+      ! Can't find graph.
+
+---
+
+    Code
+      es$weight <- 0
+    Condition
+      Error in `$<-`:
+      ! Can't find graph.
+
+# `[<-.igraph.vs` reports an internal error when the graph is unknown
+
+    Code
+      `[<-.igraph.vs`(vs, 1, value = payload)
+    Condition
+      Error in `[<-.igraph.vs`:
+      ! Graph is unknown.
+      i This is an internal error that was detected in the igraph package.
+        Please report it at <https://github.com/igraph/rigraph/issues> with a reprex (<https://tidyverse.org/help/>) and the full backtrace.
+
diff --git a/tests/testthat/test-iterators.R b/tests/testthat/test-iterators.R
index 16727ef466f..849b7d1bd6c 100644
--- a/tests/testthat/test-iterators.R
+++ b/tests/testthat/test-iterators.R
@@ -477,7 +477,56 @@ test_that("identical_graphs() tail arguments and legacy positional recovery", {
   expect_identical(res, identical_graphs(g1, g2, attrs = FALSE))
 })
 
-test_that("`[[<-.igraph.es` and `V<-` error well", {
+test_that("`V(g)[idx]$attr <-` and `E(g)[idx]$attr <-` set attributes as intended", {
+  g <- make_ring(5)
+  V(g)$color <- "red"
+  E(g)$weight <- 1:5
+
+  V(g)[1:3]$color <- "blue"
+  expect_equal(V(g)$color, c("blue", "blue", "blue", "red", "red"))
+
+  E(g)[1:3]$weight <- 0
+  expect_equal(E(g)$weight, c(0, 0, 0, 4, 5))
+
+  V(g)$color <- "green"
+  expect_equal(V(g)$color, rep("green", 5))
+
+  E(g)$weight <- 9
+  expect_equal(E(g)$weight, rep(9, 5))
+})
+
+test_that("assigning `NA` blanks attribute values without removing the attribute", {
+  g <- make_ring(5)
+  V(g)$color <- "red"
+
+  V(g)$color <- NA
+  expect_true(all(is.na(V(g)$color)))
+  expect_true("color" %in% vertex_attr_names(g))
+})
+
+test_that("assigning `NULL` errors clearly instead of silently doing nothing", {
+  # `attr(x, "value") <- NULL` removes the "value" attribute that
+  # `$<-.igraph.vs`/`$<-.igraph.es` attach, rather than attaching a NULL
+  # value. That made `V(g)$attr <- NULL` (the base R idiom for removing a
+  # list/data.frame element) a silent no-op once the "value" attribute check
+  # was dropped. `delete_vertex_attr()`/`delete_edge_attr()` are the actual
+  # way to remove an attribute.
+  g <- make_ring(5)
+  V(g)$color <- "red"
+  E(g)$weight <- 1:5
+
+  expect_snapshot(error = TRUE, {
+    V(g)$color <- NULL
+  })
+  expect_snapshot(error = TRUE, {
+    V(g)[1:3]$color <- NULL
+  })
+  expect_snapshot(error = TRUE, {
+    E(g)$weight <- NULL
+  })
+})
+
+test_that("direct misuse of `V<-`/`E<-`/`[<-`/`[[<-` errors well", {
   g <- make_(
     ring(10),
     with_vertex_(
@@ -488,7 +537,53 @@ test_that("`[[<-.igraph.es` and `V<-` error well", {
   expect_snapshot(error = TRUE, {
     V(g) <- "blue"
   })
+  expect_snapshot(error = TRUE, {
+    E(g) <- "blue"
+  })
+  expect_snapshot(error = TRUE, {
+    V(g)[1] <- "blue"
+  })
   expect_snapshot(error = TRUE, {
     E(g)[1] <- "blue"
   })
+  expect_snapshot(error = TRUE, {
+    V(g)[[1]] <- "blue"
+  })
+  expect_snapshot(error = TRUE, {
+    E(g)[[1]] <- "blue"
+  })
+})
+
+test_that("querying or setting attributes errors when the graph is unknown", {
+  g <- make_ring(5)
+  V(g)$color <- "red"
+  E(g)$weight <- 1:5
+
+  vs <- V(g)
+  attr(vs, "env") <- NULL
+  es <- E(g)
+  attr(es, "env") <- NULL
+
+  expect_snapshot(error = TRUE, vs$color)
+  expect_snapshot(error = TRUE, {
+    vs$color <- "blue"
+  })
+  expect_snapshot(error = TRUE, es$weight)
+  expect_snapshot(error = TRUE, {
+    es$weight <- 0
+  })
+})
+
+test_that("`[<-.igraph.vs` reports an internal error when the graph is unknown", {
+  # Defensive branch flagged in PR #2006 review as possibly disappearing
+  # once attribute handling is reworked -- kept here as cheap insurance,
+  # not exhaustive coverage.
+  g <- make_ring(5)
+  vs <- V(g)
+  attr(vs, "env") <- NULL
+  payload <- structure(1, name = "color", value = "blue")
+
+  expect_snapshot(error = TRUE, {
+    `[<-.igraph.vs`(vs, 1, value = payload)
+  })
 })

From 59eec13109805aa486ead63266a37b9d13757d25 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 26 Aug 2026 15:27:06 +0200
Subject: [PATCH 03/10] expand attribute removal

---
 R/iterators.R                      | 16 ++++++++++++--
 tests/testthat/_snaps/iterators.md | 24 +++++++++++++-------
 tests/testthat/test-iterators.R    | 35 ++++++++++++++++++++++++------
 3 files changed, 58 insertions(+), 17 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index 5b9983b5f68..ad877624899 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1200,7 +1200,10 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (!rlang::has_name(attributes(value), "name")) {
     cli::cli_abort("Can't find {.val name} for attribute.")
   }
-  if (!rlang::has_name(attributes(value), "value")) {
+  if (
+    !rlang::has_name(attributes(value), "value") &&
+      !is_complete_iterator(value)
+  ) {
     cli::cli_abort(
       "Can't find {.val value} for attribute. To remove an attribute, use {.fn delete_vertex_attr} instead."
     )
@@ -1224,7 +1227,10 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (!rlang::has_name(attributes(value), "name")) {
     cli::cli_abort("Can't find {.val name} for attribute.")
   }
-  if (!rlang::has_name(attributes(value), "value")) {
+  if (
+    !rlang::has_name(attributes(value), "value") &&
+      !is_complete_iterator(value)
+  ) {
     cli::cli_abort(
       "Can't find {.val value} for attribute. To remove an attribute, use {.fn delete_edge_attr} instead."
     )
@@ -1397,6 +1403,9 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort("Can't find {.val name} for vertex attribute.")
   }
   if (!rlang::has_name(attributes(value), "value")) {
+    if (is_complete_iterator(value)) {
+      return(delete_vertex_attr(x, attr(value, "name")))
+    }
     cli::cli_abort(
       "Can't find {.val value} for vertex attribute. To remove an attribute, use {.fn delete_vertex_attr} instead."
     )
@@ -1423,6 +1432,9 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort("Can't find {.val name} for edge attribute.")
   }
   if (!rlang::has_name(attributes(value), "value")) {
+    if (is_complete_iterator(value)) {
+      return(delete_edge_attr(x, attr(value, "name")))
+    }
     cli::cli_abort(
       "Can't find {.val value} for edge attribute. To remove an attribute, use {.fn delete_edge_attr} instead."
     )
diff --git a/tests/testthat/_snaps/iterators.md b/tests/testthat/_snaps/iterators.md
index 608b22d090f..d716af5cdbf 100644
--- a/tests/testthat/_snaps/iterators.md
+++ b/tests/testthat/_snaps/iterators.md
@@ -108,29 +108,37 @@
       Error in `FUN()`:
       ! Logical index length does not match the number of edges. Recycling is not allowed.
 
-# assigning `NULL` errors clearly instead of silently doing nothing
+# assigning `NULL` to a subset of vertices/edges errors instead of silently doing nothing
 
     Code
-      V(g)$color <- NULL
+      V(g)[1:3]$color <- NULL
     Condition
-      Error in `V<-`:
-      ! Can't find "value" for vertex attribute. To remove an attribute, use `delete_vertex_attr()` instead.
+      Error in `[<-`:
+      ! Can't find "value" for attribute. To remove an attribute, use `delete_vertex_attr()` instead.
 
 ---
 
     Code
-      V(g)[1:3]$color <- NULL
+      E(g)[1:3]$weight <- NULL
     Condition
       Error in `[<-`:
-      ! Can't find "value" for attribute. To remove an attribute, use `delete_vertex_attr()` instead.
+      ! Can't find "value" for attribute. To remove an attribute, use `delete_edge_attr()` instead.
+
+# assigning `NULL` for a non-existent attribute errors like `delete_vertex_attr()`/`delete_edge_attr()`
+
+    Code
+      V(g)$color <- NULL
+    Condition
+      Error in `delete_vertex_attr()`:
+      ! No vertex attribute `color` found.
 
 ---
 
     Code
       E(g)$weight <- NULL
     Condition
-      Error in `E<-`:
-      ! Can't find "value" for edge attribute. To remove an attribute, use `delete_edge_attr()` instead.
+      Error in `delete_edge_attr()`:
+      ! No edge attribute `weight` found.
 
 # direct misuse of `V<-`/`E<-`/`[<-`/`[[<-` errors well
 
diff --git a/tests/testthat/test-iterators.R b/tests/testthat/test-iterators.R
index 849b7d1bd6c..15bdbd6b961 100644
--- a/tests/testthat/test-iterators.R
+++ b/tests/testthat/test-iterators.R
@@ -504,22 +504,43 @@ test_that("assigning `NA` blanks attribute values without removing the attribute
   expect_true("color" %in% vertex_attr_names(g))
 })
 
-test_that("assigning `NULL` errors clearly instead of silently doing nothing", {
+test_that("assigning `NULL` to the full sequence removes the attribute", {
+  g <- make_ring(5)
+  V(g)$color <- "red"
+  E(g)$weight <- 1:5
+
+  V(g)$color <- NULL
+  expect_false("color" %in% vertex_attr_names(g))
+
+  E(g)$weight <- NULL
+  expect_false("weight" %in% edge_attr_names(g))
+})
+
+test_that("assigning `NULL` to a subset of vertices/edges errors instead of silently doing nothing", {
   # `attr(x, "value") <- NULL` removes the "value" attribute that
   # `$<-.igraph.vs`/`$<-.igraph.es` attach, rather than attaching a NULL
-  # value. That made `V(g)$attr <- NULL` (the base R idiom for removing a
-  # list/data.frame element) a silent no-op once the "value" attribute check
-  # was dropped. `delete_vertex_attr()`/`delete_edge_attr()` are the actual
-  # way to remove an attribute.
+  # value, so a sentinel is stored instead to mark removal intent
+  # (see `.igraph_attr_removal_sentinel`). Removing an attribute only makes
+  # sense for the full vertex/edge sequence; indexed assignment can't
+  # partially remove an attribute, so it errors clearly instead of doing
+  # nothing.
   g <- make_ring(5)
   V(g)$color <- "red"
   E(g)$weight <- 1:5
 
   expect_snapshot(error = TRUE, {
-    V(g)$color <- NULL
+    V(g)[1:3]$color <- NULL
   })
   expect_snapshot(error = TRUE, {
-    V(g)[1:3]$color <- NULL
+    E(g)[1:3]$weight <- NULL
+  })
+})
+
+test_that("assigning `NULL` for a non-existent attribute errors like `delete_vertex_attr()`/`delete_edge_attr()`", {
+  g <- make_ring(5)
+
+  expect_snapshot(error = TRUE, {
+    V(g)$color <- NULL
   })
   expect_snapshot(error = TRUE, {
     E(g)$weight <- NULL

From 588cec27e042fa4099c35cd6ccb1064f2780d4a5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 26 Aug 2026 15:51:16 +0200
Subject: [PATCH 04/10] better

---
 R/iterators.R                   | 36 ++++++++++++++++-----------------
 tests/testthat/test-iterators.R |  9 +--------
 2 files changed, 19 insertions(+), 26 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index ad877624899..389cfc2c7d2 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1197,11 +1197,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @name igraph-vs-attributes
 #' @export
 `[[<-.igraph.vs` <- function(x, i, value) {
-  if (!rlang::has_name(attributes(value), "name")) {
+  if (!rlang::has_name(attributes(value), "attr_name")) {
     cli::cli_abort("Can't find {.val name} for attribute.")
   }
   if (
-    !rlang::has_name(attributes(value), "value") &&
+    !rlang::has_name(attributes(value), "attr_value") &&
       !is_complete_iterator(value)
   ) {
     cli::cli_abort(
@@ -1224,11 +1224,11 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @name igraph-es-attributes
 #' @export
 `[[<-.igraph.es` <- function(x, i, value) {
-  if (!rlang::has_name(attributes(value), "name")) {
+  if (!rlang::has_name(attributes(value), "attr_name")) {
     cli::cli_abort("Can't find {.val name} for attribute.")
   }
   if (
-    !rlang::has_name(attributes(value), "value") &&
+    !rlang::has_name(attributes(value), "attr_value") &&
       !is_complete_iterator(value)
   ) {
     cli::cli_abort(
@@ -1375,8 +1375,8 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (is.null(get_vs_graph(x))) {
     cli::cli_abort("Can't find graph.")
   }
-  attr(x, "name") <- name
-  attr(x, "value") <- value
+  attr(x, "attr_name") <- name
+  attr(x, "attr_value") <- value
   x
 }
 
@@ -1390,8 +1390,8 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   if (is.null(get_es_graph(x))) {
     cli::cli_abort("Can't find graph.")
   }
-  attr(x, "name") <- name
-  attr(x, "value") <- value
+  attr(x, "attr_name") <- name
+  attr(x, "attr_value") <- value
   x
 }
 
@@ -1399,12 +1399,12 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @export
 `V<-` <- function(x, value) {
   ensure_igraph(x)
-  if (!rlang::has_name(attributes(value), "name")) {
+  if (!rlang::has_name(attributes(value), "attr_name")) {
     cli::cli_abort("Can't find {.val name} for vertex attribute.")
   }
-  if (!rlang::has_name(attributes(value), "value")) {
+  if (!rlang::has_name(attributes(value), "attr_value")) {
     if (is_complete_iterator(value)) {
-      return(delete_vertex_attr(x, attr(value, "name")))
+      return(delete_vertex_attr(x, attr(value, "attr_name")))
     }
     cli::cli_abort(
       "Can't find {.val value} for vertex attribute. To remove an attribute, use {.fn delete_vertex_attr} instead."
@@ -1412,9 +1412,9 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   }
   i_set_vertex_attr(
     x,
-    attr(value, "name"),
+    attr(value, "attr_name"),
     index = value,
-    value = attr(value, "value"),
+    value = attr(value, "attr_value"),
     check = FALSE
   )
 }
@@ -1428,12 +1428,12 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @export
 `E<-` <- function(x, path = NULL, P = NULL, directed = NULL, value) {
   ensure_igraph(x)
-  if (!rlang::has_name(attributes(value), "name")) {
+  if (!rlang::has_name(attributes(value), "attr_name")) {
     cli::cli_abort("Can't find {.val name} for edge attribute.")
   }
-  if (!rlang::has_name(attributes(value), "value")) {
+  if (!rlang::has_name(attributes(value), "attr_value")) {
     if (is_complete_iterator(value)) {
-      return(delete_edge_attr(x, attr(value, "name")))
+      return(delete_edge_attr(x, attr(value, "attr_name")))
     }
     cli::cli_abort(
       "Can't find {.val value} for edge attribute. To remove an attribute, use {.fn delete_edge_attr} instead."
@@ -1441,9 +1441,9 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   }
   i_set_edge_attr(
     x,
-    attr(value, "name"),
+    attr(value, "attr_name"),
     index = value,
-    value = attr(value, "value"),
+    value = attr(value, "attr_value"),
     check = FALSE
   )
 }
diff --git a/tests/testthat/test-iterators.R b/tests/testthat/test-iterators.R
index 15bdbd6b961..b11d384a4e6 100644
--- a/tests/testthat/test-iterators.R
+++ b/tests/testthat/test-iterators.R
@@ -517,13 +517,6 @@ test_that("assigning `NULL` to the full sequence removes the attribute", {
 })
 
 test_that("assigning `NULL` to a subset of vertices/edges errors instead of silently doing nothing", {
-  # `attr(x, "value") <- NULL` removes the "value" attribute that
-  # `$<-.igraph.vs`/`$<-.igraph.es` attach, rather than attaching a NULL
-  # value, so a sentinel is stored instead to mark removal intent
-  # (see `.igraph_attr_removal_sentinel`). Removing an attribute only makes
-  # sense for the full vertex/edge sequence; indexed assignment can't
-  # partially remove an attribute, so it errors clearly instead of doing
-  # nothing.
   g <- make_ring(5)
   V(g)$color <- "red"
   E(g)$weight <- 1:5
@@ -602,7 +595,7 @@ test_that("`[<-.igraph.vs` reports an internal error when the graph is unknown",
   g <- make_ring(5)
   vs <- V(g)
   attr(vs, "env") <- NULL
-  payload <- structure(1, name = "color", value = "blue")
+  payload <- structure(1, attr_name = "color", attr_value = "blue")
 
   expect_snapshot(error = TRUE, {
     `[<-.igraph.vs`(vs, 1, value = payload)

From a4e0bc8e526d32515ec9330d35e85c6372d22368 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 26 Aug 2026 15:55:07 +0200
Subject: [PATCH 05/10] name name yay

---
 R/iterators.R | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index 389cfc2c7d2..cd24f34d4f1 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1412,7 +1412,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   }
   i_set_vertex_attr(
     x,
-    attr(value, "attr_name"),
+    name = attr(value, "attr_name"),
     index = value,
     value = attr(value, "attr_value"),
     check = FALSE
@@ -1441,7 +1441,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   }
   i_set_edge_attr(
     x,
-    attr(value, "attr_name"),
+    name = attr(value, "attr_name"),
     index = value,
     value = attr(value, "attr_value"),
     check = FALSE

From b36728852bc5f26b6f663317ae1db36e6fa77d18 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 26 Aug 2026 16:00:14 +0200
Subject: [PATCH 06/10] better errors

---
 R/iterators.R                      | 20 ++++++++++++++++----
 tests/testthat/_snaps/iterators.md |  6 ++++--
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index cd24f34d4f1..85d3f67a7f0 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1205,7 +1205,10 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
       !is_complete_iterator(value)
   ) {
     cli::cli_abort(
-      "Can't find {.val value} for attribute. To remove an attribute, use {.fn delete_vertex_attr} instead."
+      c(
+        "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
+        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_vertex_attr}."
+      )
     )
   }
   if (is.null(get_vs_graph(x))) {
@@ -1232,7 +1235,10 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
       !is_complete_iterator(value)
   ) {
     cli::cli_abort(
-      "Can't find {.val value} for attribute. To remove an attribute, use {.fn delete_edge_attr} instead."
+      c(
+        "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
+        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_edge_attr}."
+      )
     )
   }
   if (is.null(get_es_graph(x))) {
@@ -1407,7 +1413,10 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
       return(delete_vertex_attr(x, attr(value, "attr_name")))
     }
     cli::cli_abort(
-      "Can't find {.val value} for vertex attribute. To remove an attribute, use {.fn delete_vertex_attr} instead."
+      c(
+        "Can't find {.val value} for vertex attribute {.val {attr(value, 'attr_name')}}.",
+        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_vertex_attr}."
+      )
     )
   }
   i_set_vertex_attr(
@@ -1436,7 +1445,10 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
       return(delete_edge_attr(x, attr(value, "attr_name")))
     }
     cli::cli_abort(
-      "Can't find {.val value} for edge attribute. To remove an attribute, use {.fn delete_edge_attr} instead."
+      c(
+        "Can't find {.val value} for edge attribute {.val {attr(value, 'attr_name')}}.",
+        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_edge_attr}."
+      )
     )
   }
   i_set_edge_attr(
diff --git a/tests/testthat/_snaps/iterators.md b/tests/testthat/_snaps/iterators.md
index d716af5cdbf..69e114d58a8 100644
--- a/tests/testthat/_snaps/iterators.md
+++ b/tests/testthat/_snaps/iterators.md
@@ -114,7 +114,8 @@
       V(g)[1:3]$color <- NULL
     Condition
       Error in `[<-`:
-      ! Can't find "value" for attribute. To remove an attribute, use `delete_vertex_attr()` instead.
+      ! Can't find "value" for attribute "color".
+      i Removing an attribute is only supported for the whole vertex sequence, e.g. `V(g)$color <- NULL`, not a subset. To remove it directly, use `delete_vertex_attr()`.
 
 ---
 
@@ -122,7 +123,8 @@
       E(g)[1:3]$weight <- NULL
     Condition
       Error in `[<-`:
-      ! Can't find "value" for attribute. To remove an attribute, use `delete_edge_attr()` instead.
+      ! Can't find "value" for attribute "weight".
+      i Removing an attribute is only supported for the whole edge sequence, e.g. `E(g)$weight <- NULL`, not a subset. To remove it directly, use `delete_edge_attr()`.
 
 # assigning `NULL` for a non-existent attribute errors like `delete_vertex_attr()`/`delete_edge_attr()`
 

From a988499b5252e88796817102ae666d6dd7ff64de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 26 Aug 2026 16:06:54 +0200
Subject: [PATCH 07/10] better wording

---
 R/iterators.R                      | 8 ++++----
 tests/testthat/_snaps/iterators.md | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index 85d3f67a7f0..c383389c8d0 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1207,7 +1207,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_vertex_attr}."
+        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_vertex_attr}."
       )
     )
   }
@@ -1237,7 +1237,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_edge_attr}."
+        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_edge_attr}."
       )
     )
   }
@@ -1415,7 +1415,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for vertex attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_vertex_attr}."
+        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_vertex_attr}."
       )
     )
   }
@@ -1447,7 +1447,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for edge attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset. To remove it directly, use {.fn delete_edge_attr}."
+        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_edge_attr}."
       )
     )
   }
diff --git a/tests/testthat/_snaps/iterators.md b/tests/testthat/_snaps/iterators.md
index 69e114d58a8..067d5448c8b 100644
--- a/tests/testthat/_snaps/iterators.md
+++ b/tests/testthat/_snaps/iterators.md
@@ -115,7 +115,7 @@
     Condition
       Error in `[<-`:
       ! Can't find "value" for attribute "color".
-      i Removing an attribute is only supported for the whole vertex sequence, e.g. `V(g)$color <- NULL`, not a subset. To remove it directly, use `delete_vertex_attr()`.
+      i Removing an attribute is only supported for the whole vertex sequence, e.g. `V(g)$color <- NULL`, not a subset, or use `delete_vertex_attr()`.
 
 ---
 
@@ -124,7 +124,7 @@
     Condition
       Error in `[<-`:
       ! Can't find "value" for attribute "weight".
-      i Removing an attribute is only supported for the whole edge sequence, e.g. `E(g)$weight <- NULL`, not a subset. To remove it directly, use `delete_edge_attr()`.
+      i Removing an attribute is only supported for the whole edge sequence, e.g. `E(g)$weight <- NULL`, not a subset, or use `delete_edge_attr()`.
 
 # assigning `NULL` for a non-existent attribute errors like `delete_vertex_attr()`/`delete_edge_attr()`
 

From 85883bc93ee33cc77b200ee77e8f938d7bfdb78a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 26 Aug 2026 16:10:17 +0200
Subject: [PATCH 08/10] ok

---
 R/iterators.R                      | 8 ++++----
 tests/testthat/_snaps/iterators.md | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index c383389c8d0..f86157656ab 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1207,7 +1207,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_vertex_attr}."
+        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset. Use {.fn delete_vertex_attr}."
       )
     )
   }
@@ -1237,7 +1237,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_edge_attr}."
+        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset. Use {.fn delete_edge_attr}."
       )
     )
   }
@@ -1415,7 +1415,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for vertex attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_vertex_attr}."
+        i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset. Use {.fn delete_vertex_attr}."
       )
     )
   }
@@ -1447,7 +1447,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
     cli::cli_abort(
       c(
         "Can't find {.val value} for edge attribute {.val {attr(value, 'attr_name')}}.",
-        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset, or use {.fn delete_edge_attr}."
+        i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset. Use {.fn delete_edge_attr}."
       )
     )
   }
diff --git a/tests/testthat/_snaps/iterators.md b/tests/testthat/_snaps/iterators.md
index 067d5448c8b..01cba8e7203 100644
--- a/tests/testthat/_snaps/iterators.md
+++ b/tests/testthat/_snaps/iterators.md
@@ -115,7 +115,7 @@
     Condition
       Error in `[<-`:
       ! Can't find "value" for attribute "color".
-      i Removing an attribute is only supported for the whole vertex sequence, e.g. `V(g)$color <- NULL`, not a subset, or use `delete_vertex_attr()`.
+      i Removing an attribute is only supported for the whole vertex sequence, e.g. `V(g)$color <- NULL`, not a subset. Use `delete_vertex_attr()`.
 
 ---
 
@@ -124,7 +124,7 @@
     Condition
       Error in `[<-`:
       ! Can't find "value" for attribute "weight".
-      i Removing an attribute is only supported for the whole edge sequence, e.g. `E(g)$weight <- NULL`, not a subset, or use `delete_edge_attr()`.
+      i Removing an attribute is only supported for the whole edge sequence, e.g. `E(g)$weight <- NULL`, not a subset. Use `delete_edge_attr()`.
 
 # assigning `NULL` for a non-existent attribute errors like `delete_vertex_attr()`/`delete_edge_attr()`
 

From f46e70f9f79b64cd24aa3a9c6806774ceeadaa1e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Wed, 26 Aug 2026 16:14:45 +0200
Subject: [PATCH 09/10] more specific

---
 R/iterators.R                      |  8 ++++----
 tests/testthat/_snaps/iterators.md | 12 ++++++------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/R/iterators.R b/R/iterators.R
index f86157656ab..729a78c46ff 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -1198,7 +1198,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @export
 `[[<-.igraph.vs` <- function(x, i, value) {
   if (!rlang::has_name(attributes(value), "attr_name")) {
-    cli::cli_abort("Can't find {.val name} for attribute.")
+    cli::cli_abort("Can't find {.val name} for vertex attribute.")
   }
   if (
     !rlang::has_name(attributes(value), "attr_value") &&
@@ -1206,7 +1206,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   ) {
     cli::cli_abort(
       c(
-        "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
+        "Can't find {.val value} for vertex attribute {.val {attr(value, 'attr_name')}}.",
         i = "Removing an attribute is only supported for the whole vertex sequence, e.g. {.code V(g)${attr(value, 'attr_name')} <- NULL}, not a subset. Use {.fn delete_vertex_attr}."
       )
     )
@@ -1228,7 +1228,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
 #' @export
 `[[<-.igraph.es` <- function(x, i, value) {
   if (!rlang::has_name(attributes(value), "attr_name")) {
-    cli::cli_abort("Can't find {.val name} for attribute.")
+    cli::cli_abort("Can't find {.val name} for edge attribute.")
   }
   if (
     !rlang::has_name(attributes(value), "attr_value") &&
@@ -1236,7 +1236,7 @@ simple_es_index <- function(x, i, na_ok = FALSE) {
   ) {
     cli::cli_abort(
       c(
-        "Can't find {.val value} for attribute {.val {attr(value, 'attr_name')}}.",
+        "Can't find {.val value} for edge attribute {.val {attr(value, 'attr_name')}}.",
         i = "Removing an attribute is only supported for the whole edge sequence, e.g. {.code E(g)${attr(value, 'attr_name')} <- NULL}, not a subset. Use {.fn delete_edge_attr}."
       )
     )
diff --git a/tests/testthat/_snaps/iterators.md b/tests/testthat/_snaps/iterators.md
index 01cba8e7203..14bfdb75dfe 100644
--- a/tests/testthat/_snaps/iterators.md
+++ b/tests/testthat/_snaps/iterators.md
@@ -114,7 +114,7 @@
       V(g)[1:3]$color <- NULL
     Condition
       Error in `[<-`:
-      ! Can't find "value" for attribute "color".
+      ! Can't find "value" for vertex attribute "color".
       i Removing an attribute is only supported for the whole vertex sequence, e.g. `V(g)$color <- NULL`, not a subset. Use `delete_vertex_attr()`.
 
 ---
@@ -123,7 +123,7 @@
       E(g)[1:3]$weight <- NULL
     Condition
       Error in `[<-`:
-      ! Can't find "value" for attribute "weight".
+      ! Can't find "value" for edge attribute "weight".
       i Removing an attribute is only supported for the whole edge sequence, e.g. `E(g)$weight <- NULL`, not a subset. Use `delete_edge_attr()`.
 
 # assigning `NULL` for a non-existent attribute errors like `delete_vertex_attr()`/`delete_edge_attr()`
@@ -164,7 +164,7 @@
       V(g)[1] <- "blue"
     Condition
       Error in `[<-`:
-      ! Can't find "name" for attribute.
+      ! Can't find "name" for vertex attribute.
 
 ---
 
@@ -172,7 +172,7 @@
       E(g)[1] <- "blue"
     Condition
       Error in `[<-`:
-      ! Can't find "name" for attribute.
+      ! Can't find "name" for edge attribute.
 
 ---
 
@@ -180,7 +180,7 @@
       V(g)[[1]] <- "blue"
     Condition
       Error in `[[<-`:
-      ! Can't find "name" for attribute.
+      ! Can't find "name" for vertex attribute.
 
 ---
 
@@ -188,7 +188,7 @@
       E(g)[[1]] <- "blue"
     Condition
       Error in `[[<-`:
-      ! Can't find "name" for attribute.
+      ! Can't find "name" for edge attribute.
 
 # querying or setting attributes errors when the graph is unknown
 

From 35ad09fa6b7b044855800edb71a7e1f1eb286c40 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ABlle=20Salmon?= <maelle.salmon@yahoo.se>
Date: Tue, 8 Sep 2026 09:59:17 +0200
Subject: [PATCH 10/10] change to `isTRUE()`

---
 R/iterators.R | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/R/iterators.R b/R/iterators.R
index 2ecad58faed..0b94db77a83 100644
--- a/R/iterators.R
+++ b/R/iterators.R
@@ -182,7 +182,7 @@ graph_id.igraph.es <- function(x, ...) {
 }
 
 is_complete_iterator <- function(x) {
-  identical(attr(x, "is_all"), TRUE)
+  isTRUE(attr(x, "is_all"))
 }
 
 set_complete_iterator <- function(x, value = TRUE) {