app/controllers/courses_controller.rb:1:in `<top (required)>'app/controllers/courses_controller.rb:1:in `<top (required)>'undefined method `key?' for nil:NilClass
app/controllers/courses_controller.rb:1:in `<top (required)>'app/controllers/courses_controller.rb:1:in `<top (required)>'undefined method `key?' for nil:NilClass
