Hello @JTR,
Welcome to the forum.
We all have to start somewhere!
This is a good starting point:
Welcome to the Processing Foundation Discourse << See Guidelines Asking Questions.
It is important to isolate the issue!
Scale it down to an MCVE (see guidelines for this) and this will help isolate it.
That is a common error… and not always so simple to find.
Reference:
I did not get errors in this code block (similar to yours with variables initialized):
Look outside of the code you provided for the source of the error.
:)