Collection can't handle array of text fields

[kmotsov]

Having a serialized array attribute in a model

model Sample
  serialize :links, Array, prepopulate: -> (*) { self.links = links + Array.new(3 - self.links.size, '') }
end

and a reform object

class SampleForm < Reform::Form
  collection :links
end

In order to allow changing links my form is expected to render 3 inputs with name attributes links[].
However it is not possible to be achieved using formulars' collection method.

When I tried creating a slim view:

= vertical_form(model.contract, url) do |f|
  = f.collection :links
  = f.submit content: "Submit!"

It fails rendering with undefined method 'errors' for "":String