undefined method `clear' for nil:NilClass when attempting precompile

[tdwalton]

I get the following error output when attempting to precompile assets, in Rails 3.2.17.

myapp@beta-gateway1 ~/payment_segmentation $ RAILS_ENV=beta RAILS_GROUPS=assets bundle exec rake assets:precompile --trace
AssetSync: using /home/myapp/payment_segmentation/config/initializers/asset_sync.rb
** Invoke assets:precompile (first_time)
** Execute assets:precompile
** Invoke assets:precompile:all (first_time)
** Invoke assets:cache:clean (first_time)
** Invoke assets:environment (first_time)
** Execute assets:environment
** Invoke environment (first_time)
** Execute environment
** Execute assets:cache:clean
rake aborted!
undefined method `clear' for nil:NilClass
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/tasks/assets.rake:184:in `block (3 levels) in <top (required)>'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:228:in `call'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:228:in `block in execute'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:223:in `each'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:223:in `execute'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:166:in `block in invoke_with_call_chain'
/home/myapp/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:159:in `invoke_with_call_chain'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:187:in `block in invoke_prerequisites'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:185:in `each'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:185:in `invoke_prerequisites'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:165:in `block in invoke_with_call_chain'
/home/myapp/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:159:in `invoke_with_call_chain'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:152:in `invoke'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/tasks/assets.rake:35:in `invoke_or_reboot_rake_task'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/tasks/assets.rake:50:in `block (2 levels) in <top (required)>'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:228:in `call'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:228:in `block in execute'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:223:in `each'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:223:in `execute'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:166:in `block in invoke_with_call_chain'
/home/myapp/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:159:in `invoke_with_call_chain'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/task.rb:152:in `invoke'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:143:in `invoke_task'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:101:in `block (2 levels) in top_level'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:101:in `each'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:101:in `block in top_level'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:110:in `run_with_threads'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:95:in `top_level'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:73:in `block in run'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:160:in `standard_exception_handling'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/lib/rake/application.rb:70:in `run'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/gems/rake-10.0.3/bin/rake:33:in `<top (required)>'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/bin/rake:23:in `load'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/bin/rake:23:in `<main>'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/bin/ruby_executable_hooks:15:in `eval'
/home/myapp/.rvm/gems/ruby-1.9.3-p484@myapp/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => assets:precompile:all => assets:cache:clean

If I replace:

 namespace :cache do
    task :clean => ["assets:environment"] do
      FileUtils.mkdir_p(File.join(::Rails.root.to_s, *%w(tmp cache assets)))
        ::Rails.application.assets.cache.clear
    end
  end

with:

 namespace :cache do
    task :clean => ["assets:environment"] do
      FileUtils.mkdir_p(File.join(::Rails.root.to_s, *%w(tmp cache assets)))
      if ::Rails.application.assets.cache
          ::Rails.application.assets.cache.clear
      end
    end
  end

in /lib/turbo-sprockets/tasks/assets.rake, the error goes away, and asset compilation works.

I'd submit a pull request, but I'm not sure this is the correct fix, as it's not clear to me why ::Rails.application.assets.cache is nil.

Please advise.

[austinrfnd]

@ndbroadbent let me know if we have to modify the pull request in any way. Thank you!