So after looking through the logic of how that could have happened, you must have gotten to a forest, had an event that wasn't the hell opens event, then entered the forest.
I'll add a clause preventing it from happening in subworlds. In the meantime a workaround is to avoid level 4+ nodes in subworlds until the hell opens event has actually happened. Hopefully you can either get through or get to another place where it's safe to trigger it.