sprockets-rails 3.0.0 release: undefined method `register_preprocessor' for nil:NilClass

[mikeantonelli]

With the release of sprockets-rails 3.0.0 today, my Ruby on Rails Engines started failing to initialize during continuous integration with:

less-rails-2.7.0/lib/less/rails/railtie.rb:23:in `block in <class:Railtie>': undefined method `register_preprocessor' for nil:NilClass (NoMethodError)
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `instance_exec'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `run'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/railties-4.2.0/lib/rails/initializable.rb:55:in `block in run_initializers'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:226:in `block in tsort_each'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:348:in `block (2 levels) in each_strongly_connected_component'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:427:in `each_strongly_connected_component_from'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:347:in `block in each_strongly_connected_component'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:345:in `each'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:345:in `call'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:345:in `each_strongly_connected_component'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:224:in `tsort_each'
  from ~/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/tsort.rb:205:in `tsort_each'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/railties-4.2.0/lib/rails/initializable.rb:54:in `run_initializers'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/railties-4.2.0/lib/rails/application.rb:352:in `initialize!'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/railties-4.2.0/lib/rails/railtie.rb:194:in `public_send'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/railties-4.2.0/lib/rails/railtie.rb:194:in `method_missing'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/combustion-0.5.3/lib/combustion.rb:34:in `initialize!'
  from ~/Development/my_rails_engine/spec/rails_helper.rb:18:in `<top (required)>'
  from ~/Development/my_rails_engine/spec/controllers/my_rails_engine/encounters_controller_spec.rb:1:in `require'
  from ~/Development/my_rails_engine/spec/controllers/my_rails_engine/encounters_controller_spec.rb:1:in `<top (required)>'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1361:in `load'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1361:in `block in load_spec_files'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1359:in `each'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/configuration.rb:1359:in `load_spec_files'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:102:in `setup'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:88:in `run'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:73:in `run'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/lib/rspec/core/runner.rb:41:in `invoke'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/gems/rspec-core-3.4.1/exe/rspec:4:in `<top (required)>'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/bin/rspec:23:in `load'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/bin/rspec:23:in `<main>'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/bin/ruby_executable_hooks:15:in `eval'
  from ~/.rvm/gems/ruby-2.1.3@my_rails_engine/bin/ruby_executable_hooks:15:in `<main>'

Rails trusts sprockets-rails >= 2.0.0. I'm still working through the exact error but locking to ~> 2.3 resolved the problem - should this dependency's version lock differently?

[matthewd]

That error doesn't seem to be coming from Rails.

[u007]

its still happening, due to sprocket-rails 3.0
currently working:
sprocketrails 2.3.3 + sprockets (3.5.2)

[u007]

can this issue be reopen?

[matthewd]

@u007 the backtrace in this issue shows the exception is coming from less-rails. This is not a Rails issue.