It happened in an onslaught invasion, I was killing penghouls from fish's undead rising (they were part of the raid) and I crashed
https://gist.github.com/mxnmnm/4ff1d7096bcb902d290fee619ae132c7

This is for 1.12 so I hope it still has support

Unfortunately as this is before 1.16.5, I can't do much on it. I think the best best here is to disable elite AIs on the type of mob that crashed with it. That said, these kinds of crashes should not cause any damage to the world, so if this crash is rare enough, you could just leave it as-is.