Oh thank you for telling me about that, I actually haven't seen that error! I'll look into that, and update the demo with a fix as well when I can
I was able to beat a different boss on that floor, on a different floor I got the bat boss but this time if worked just fine. I think the issue only occurs if there is an open room to the right of the boss room.
Right on, thanks for the insight. There's definitely still some janky stuff like that which needs to be fixed.