If I'm reading that traceback correctly (which I could be very wrong), it appears you have started a game with over 200 rnpc. If that's the case, you might be running into memory errors due to how many rnpc's the game is trying to keep track of.
any way to remove one without restarting?
Not that I'm aware of. It might be possible with a mod, but I can't say for sure, because I'm not a programmer.
EDIT: Removed typo.
