Alot of people seem to be getting the same Unkown Error message, I don't think it's because of a message you're explicitely sending but rather the test case is not completely passed and maybe as a result this is a default message that is shown becuase a condition is not satisfied? A try catch won't be helpful since my code ran without error but it was due to the unseen test conditions that it failed.

Unknown error is not enough feedback. When I got it, I narrowed it down to two issues before being able to fully subit. 1) need to check for null source and 2) uppercase letters need to stay as is in final unless it is a dictionary letter for the leetspeak