NoMethodError error on enum with _default option set

[clinejj]

We have a class with the following definition:

# == Schema Information
#
# Table name: product_filters
#
#  id               :bigint           not null, primary key
#  display_text_key :string
#  filter_type      :integer          default("select_multiple")
#  created_at       :datetime         not null
#  updated_at       :datetime         not null
#
# Indexes
#
#  index_product_filters_on_display_text_key  (display_text_key) UNIQUE
#
class ProductFilter < ApplicationRecord
  enum filter_type: { select_multiple: 0, select_single: 1, range: 2, text: 3 }, _default: :select_multiple
end

when running bin/rails rbs_rails:all --trace we get the following error:

** Invoke rbs_rails:all (first_time)
** Invoke rbs_rails:generate_rbs_for_models (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute rbs_rails:generate_rbs_for_models
rails aborted!
NoMethodError: undefined method `each' for :select_multiple:Symbol
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:246:in `block (2 levels) in enum_instance_methods'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:243:in `each'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:243:in `block in enum_instance_methods'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:242:in `each'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:242:in `enum_instance_methods'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:37:in `klass_decl'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:25:in `generate'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/active_record.rb:11:in `class_to_rbs'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/rake_task.rb:45:in `block (2 levels) in def_generate_rbs_for_models'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/rake_task.rb:38:in `each'
/gem_cache/ruby/3.0.0/gems/rbs_rails-0.9.0/lib/rbs_rails/rake_task.rb:38:in `block in def_generate_rbs_for_models'
/gem_cache/ruby/3.0.0/gems/rake-13.0.6/lib/rake/task.rb:281:in `block in execute'

The task completes as expected if the _default option is commented out, like so:

class ProductFilter < ApplicationRecord
  enum filter_type: { select_multiple: 0, select_single: 1, range: 2, text: 3 } #, _default: :select_multiple
end