I am still working on the course. I originally got a 90 on the assignment. After (re)going over the assignment, I found the error. However, although the lab loads and is editable (otherwise I wouldn’t have been able to run and test the function producing the error), there is no “Submit” button showing.
I’d recommend to download/rename your current assignment file and fetch a fresh copy (the instructions for which can be found in the first week, before the first assignment) of the assignment. Let me know if doing that fixes anything.