rails/rails — pull request #16802 by mnieborak (2014-09-04 18:32:42+00:00)
Title: Change error message for typo in helper's name

I've tried to make the error message more helpful, when helper name is misspelled. I created new type of error (MissingHelperModuleError) which is raised when expected constant is not loaded. I'd appreciate any feedback about my solution.