I managed to load the game without crashing. I think the crashing was related to some sort of bug with the tear in reality when a monster comes through, and it just didn’t happen this time.
EDIT: There is now a flying polyp, a gracken, a yugg, three blank bodies, and one dead mi-go. It may have been a bug with the mi-go’s speech, and the thing was killed before it could say the bugged phrase. I’ll look out for more crashes around both mi-goes and tears in reality.