Attempting to use an inline representer with Representable 1.6.0

inline_representer.rb

require 'pp'
require 'representable/json'

class Album < Struct.new(:name, :songs); end
class Song < Struct.new(:title, :track); end

module AlbumPresenter
  include Representable::JSON

  property :name

  collection :songs, class: Song do
    property :title
    property :track
  end
end

album = Album.new('Lincoln', [
  Song.new('Ana Ng', 1),
  Song.new('Cowtown', 2),
  Song.new('Lie Still, Little Bottle', 3)
])

pp album.extend(AlbumPresenter).to_json

results.txt

$ ruby inline_representer.rb 
/Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/binding.rb:139:in `serialize': undefined method `to_hash' for #<struct Song title="Ana Ng", track=1> (NoMethodError)
  from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/bindings/hash_bindings.rb:54:in `block in serialize_for'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/bindings/hash_bindings.rb:54:in `collect'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/bindings/hash_bindings.rb:54:in `serialize_for'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/bindings/hash_bindings.rb:38:in `write'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/binding.rb:57:in `write_fragment_for'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/binding.rb:52:in `write_fragment'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/binding.rb:36:in `block in compile_fragment'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/binding.rb:93:in `represented_exec_for'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/binding.rb:35:in `compile_fragment'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/mapper.rb:67:in `compile_fragment'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/mapper.rb:35:in `serialize_property'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/feature/readable_writeable.rb:11:in `serialize_property'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/mapper.rb:25:in `block in serialize'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/mapper.rb:24:in `each'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/mapper.rb:24:in `serialize'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable.rb:28:in `create_representation_with'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/hash.rb:38:in `to_hash'
	from /Users/rsutphin/.rvm/gems/ruby-1.9.3-p448/gems/representable-1.6.0/lib/representable/json.rb:40:in `to_json'
	from inline_representer.rb:24:in `<main>'

See apotonick/representable#54 for the fix.