return statement in if statement

id like to know why the tutor doesn't explain the use of the return statement in his if statement at the time of writing it........... i have spent many hours trying to resolve the errors in my console and did resolve them with the addition of a return statement, but why does the tutor not even mention those errors at the time of writing the if statement, he doesn't even acknowledge that the error exists until several lessons down the line, when i got those errors i thought i had done something wrong or incorrect ESPECIALLY since the tutor doesn't even acknowledge the errors in the video. and spent REALLY long time wondering where i had gone wrong etc, it would have saved me a on of time and frustration if the teacher had said "this will cause the following errors to occur in your console, but don't worry about that, we can fix it with a return statement" rather than waiting till several lessons down the line to explain the error and the solution. very annoyed by that.