NoMethodError: undefined method `new'

[dt1973]

I just deleted and recloned my Rails app. I've been using ruby-clean-css for CSS minification for a while now and it's all been great, but now all of a sudden I'm getting this:

% bundle exec rake assets:precompile RAILS_ENV=production
rake aborted!
NoMethodError: undefined method `new' for #<RubyCleanCSS::Compressor:0x00000 812414de8 @js_options={}>
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ legacy_tilt_processor.rb:25:in `call'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ processor_utils.rb:75:in `call_processor'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ processor_utils.rb:57:in `block in call_processors'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ processor_utils.rb:56:in `reverse_each'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ processor_utils.rb:56:in `call_processors'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ loader.rb:86:in `load_asset_by_uri'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ loader.rb:45:in `block in load'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ loader.rb:155:in `fetch_asset_from_dependency_cache'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ loader.rb:38:in `load'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ cached_environment.rb:20:in `block in initialize'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ cached_environment.rb:47:in `yield'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ cached_environment.rb:47:in `load'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ base.rb:63:in `find_asset'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ base.rb:70:in `find_all_linked_assets'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ manifest.rb:130:in `block in find'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ manifest.rb:129:in `each'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ manifest.rb:129:in `find'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/sprockets/ manifest.rb:162:in `compile'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.3.1/lib/spro ckets/rails/task.rb:70:in `block (3 levels) in define'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-3.2.0/lib/rake/sproc ketstask.rb:147:in `with_logger'
/home/example/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.3.1/lib/spro ckets/rails/task.rb:69:in `block (2 levels) in define'
Tasks: TOP => assets:precompile
(See full trace by running task with --trace)

environments/production.rb

config.assets.css_compressor = :cleancss

Gemfile

gem "ruby-clean-css"