Monsters triggering door collapse don't trigger a message
I went to PC:3, and was in a room with one door. Trying to open the door resulted in a locked message, so I pressed w5 to heal before tempting traps/guards. The door disappeared while I was resting with no message and some (not-mimic) gold was behind it, no monster and no door (open or closed, blank tile). I asked about it on IRC and popular opinion is that it was a collapsing door that crushed and killed the monster who tried to open it. If that's the case, and it probably is, then it should have a message. Something like "You see a door collapse onto -foo-."