Different behaviour for mount_on with blank values between 1.3.1 and 2.1.0

[schinery]

I've just been upgrading some projects that use Carrierwave, and have stumbled upon a change in behaviour that is causing me some problems, and I want to check if I've missed something as part of the upgrade.

This is the existing DB schema which was created pre 1.3.1:

create_table "things", id: :uuid, default: -> { "uuid_generate_v4()" }, force: :cascade do |t|
  t.text "filenames", default: [], array: true
end

This is the existing model that has the mount_uploaders added to it:

class Thing < ApplicationRecord
  mount_uploaders :files, FilesUploader, mount_on: :filenames
end

In Carrierwave 1.3.1 if I was to find a Thing object with no filenames currently set it would return a blank array on the object.

thing = Thing.find("92773c7b-6341-411e-980b-4073531f5c53")
#<Thing id: "92773c7b-6341-411e-980b-4073531f5c53", filenames: []>

In 2.1.0 though, it returns filenames as nil.

thing = Thing.find("92773c7b-6341-411e-980b-4073531f5c53")
#<Thing id: "92773c7b-6341-411e-980b-4073531f5c53", filenames: nil>

This is causing me problems where I had existing code that was doing something like thing.filenames + params[:filenames] because it is now trying to use + on nil. I know I can cast using Array(thing.filenames) but wanted to see if there was reason for this change or whether I need to do something else in my code?