A lot of people, including myself, are encountering frustrating issues with some courses that require you to output/return a given string in order to pass the lesson. A lot of strings are formatted with proper punctuation, and check for that punctuation in the result. If it is missing, the lesson fails and tells you to try again. It does not give clear guidance on what went wrong, often even giving an error that sends you looking at the wrong part of your code!
My suggestion is to either relax these text checks on a course to simply verify the code is correct without necessarily needing an exact line of text, or instead of using specific text as output, use boolean statements to test (for example, in the JavaScript courses for conditional statements, instead of requiring return "this function passed." or return "this function failed.", just use return falseorreturn true`. This already exists in a very small handful of lessons, but I propose it be the standard way of verifying a function’s operation.
In lessons where it is absolutely necessary to have exact text (such as in if… else lessons where multiple return statements are necessary), either use another variable (such as return 1... 2... 3... 4 instead of return 'A... B... C... D') or changing the verification to ignore punctuation and only verify the letter/word itself is present.
A final possibility is to add an explicit instruction to each error to double-check the spelling in your return statement. This already happens on some lessons, but as I mentioned, many lessons direct you to verify syntax errors or some other, unrelated error.