Sprockets::ArgumentError in Main#index

[aliabbas-2012]

Showing /home/ali/railsprojects/rails-angular-tutorial/part-3/app/views/layouts/application.html.erb where line #6 raised:

require_tree argument must be a directory (in /home/ali/railsprojects/rails-angular-tutorial/part-3/app/assets/javascripts/main.js.coffee:7)

<%= javascript_include_tag "application", controller_name %>

This line is giving eroor, please tell me how to run this thanks