> <email deleted>
> Oops! [...]
> Suddenly, the dungeon collapses.
> place_object: obj not free
>
> The crash is reproducible in wizmode by wishing for a landmine, arming it and
> pushing a wished-for boulder onto it.
Make pushing a boulder onto a landmine share code with the trap case,
resulting in pits, waking sleepers, et al.
Don't leave a boulder suspended over the new pit, fill it.
Make sure any remaining boulder is placed on top of the pile.
If player sets off landmine, monsters killed are credited to/blamed on player.