I didn't realise it was possible to softlock there, I'm sorry you had to go through that! Whenever I take the time to make a full version I'll make sure to either put a check point there, or rework how my keys and doors are handled... Also, yeah, the stairs were deliberately put there in order to prevent you from backtracking, thus locking you in the area that has a key and a door, which was meant to prevent any softlocks, but I neglected the fact that death was a possibility... Stupid me...