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.

Fixes #16468
Then the first order of business is to reproduce that error in the tests :wink: I'll take a look at it tomorrow.