What's funny is that I don't use the ^= expression except in one place and commenting that line doesn't stop the error.
It seems to be happening whenever you click anywhere.
Anyway, I wasn't worried about the error until now because I'm having difficulty with a new function I'm writing that works fine in jsFiddle, but doesn't complete executing and also doesn't throw and error that's logged in the console.
If anyone has any advice on what to do to try and figure this all out, I'd be very appreciative.