Exception "TypeError: no implicit conversion of nil into String" when listing files in section

[neilabdev]

While trying to use the bcms_kcfinder module in rails 3.2.22.2 and BrowserCMS 3.5.7, I notice it was receiving various errors, which I traced back to an exception cause when trying to list files in a given section. To test, you can run the following in the console:

@section = Cms::Section.last
Cms::ImageBlock.by_section(@section)

Which Returns:

2.3.0 :002 > Cms::ImageBlock.by_section(@section)
  Cms::SectionNode Load (0.2ms)  SELECT `section_nodes`.* FROM `section_nodes` WHERE `section_nodes`.`node_id` = 3 AND `section_nodes`.`node_type` = 'Cms::Section' LIMIT 1
TypeError: no implicit conversion of nil into String
    from /Users/ghost/.rvm/gems/ruby-2.3.0@csp_development/gems/arel-3.0.3/lib/arel.rb:40:in `initialize'
    from /Users/ghost/.rvm/gems/ruby-2.3.0@csp_development/gems/arel-3.0.3/lib/arel.rb:40:in `new'
    from /Users/ghost/.rvm/gems/ruby-2.3.0@csp_development/gems/arel-3.0.3/lib/arel.rb:40:in `sql'
    from /Users/ghost/.rvm/gems/ruby-2.3.0@csp_development/gems/activerecord-3.2.22.2/lib/active_record/associations/join_helper.rb:47:in `block in sanitize'
    from /Users/ghost/.rvm/gems/ruby-2.3.0@csp_development/gems/activerecord-3.2.22.2/lib/active_record/associations/join_helper.rb:45:in `map'
    from /Users/ghost/.rvm/gems/ruby-2.3.0@csp_development/gems/activerecord-3.2.22.2/lib/active_record/associations/join_helper.rb:45:in `sanitize'
    from /Users/ghost/.rvm/gems/ruby-2.3.0@csp_development/gems/activerecord-3.2.22.2/lib/active_record/associations/join_dependency/join_association

The file causing the issue:

#app/assets/models/cms/abstract_file_block.rb
module Cms
  class AbstractFileBlock < ActiveRecord::Base
    self.table_name = Namespacing.prefix("file_blocks")
    validates_presence_of :name

    ### Error caused Here
    scope :by_section, lambda { |section| {
       :include => {:attachments => :section_node},
        :conditions => ["#{SectionNode.table_name}.ancestry = ?", section.node.ancestry_path]}
    }
  end
end

[neilabdev]

Turns out to be a bug in ruby when version 2.3.0 and other versions. Version ruby-2.2.3 and ruby-2.0.0-p648 seem to work just fine. Its actually the difference in output of the interolate function when building the query that fails:

# activerecord-3.2.22.2/lib/active_record/associations/join_dependency/join_association.rb
def interpolate(conditions)
  if conditions.respond_to?(:to_proc)
    instance_eval(&conditions) # this returns nil when the failure occurs, other versions don't fail here.
  else
    conditions
  end
end