bug in my code

[sparkz_alot]

You are getting an error, because you are telling Python to generate an error, so Python says "okee dokee here's an error"

If you don't want that, try something like:

   elif not cat.isalpha():
     print("not alpha")
     break

Just a matter of semantics, but your response "Argument should be a string", is not really accurate,  since at the beginning of your function you are converting every thing to a string.