global.lua crash-loops every onUpdate on OpenMW 0.51.0 (cell.region is now nil, not empty string, for regionless cells)

[cwilliams-98]

This report was drafted by an AI assistant (Claude) on my behalf, based on analysis of my openmw.log — I'm not a programmer or an experienced Morrowind modder, so please bear with me if there are follow-up technical questions.

Environment

• OpenMW 0.51.0 (Windows)
• Large mod list including Tamriel Rebuilt + OAAB (many interior and mainland cells)

Symptom

scripts/DynamicMusic/global.lua throws on essentially every engine tick for the entire play session:

Global[scripts/dynamicmusic/global.lua] onUpdate failed. Lua error: [string "scripts/dynamicmusic/global.lua"]:25: table index is nil

In one ~2.5 hour session this logged 1,058,943 times, from shortly after load until quit — it never stops or self-heals.

Root cause

sendGlobalData() does:

for _, cell in ipairs(world.cells) do
  if cell.name ~= '' then
    table.insert(cellNames, cell.name)
  end
  regionNamesSet[cell.region] = true   -- line 25
end

cell.region is nil for any cell with no region (all interior cells, for example). Indexing a table with a nil key is a hard Lua error, so this throws the moment the loop hits the first such cell.

This used to be safe because OpenMW's Lua API returned an empty string "" for a regionless cell rather than nil — a valid table key. OpenMW 0.51.0 changed that: per the 0.51.0 release notes and GitLab #8718 ("Cell fields can still return empty strings instead of nil values"), empty CellT fields — including region — are now consistently exposed as nil. The current docs confirm this: "Region of the cell (can be nil)." So this script silently broke as a side effect of upgrading to 0.51.0, not because of anything mod-list-specific.

Because the error happens inside sendGlobalData, execution never reaches players[player.id] = true in onUpdate, so the "already sent" guard never gets set — the mod retries (and fails) again on every subsequent tick for the rest of the session.

Suggested fix

Guard the nil case before using it as a key:

if cell.region then
  regionNamesSet[cell.region] = true
end

Happy to test a fix if useful. Thanks for the mod!