When you break the second plaster obstacle, a pit opens up (see PLASTER-FCN) and everything in the room falls into it. This is handled by DUMP-ALL-ON-GROUND.
But this function does not check if the room just went dark, so even if your torch falls into the pit the room remains lit. If you leave and re-enter the room, it's dark as it should be.
When you break the second plaster obstacle, a pit opens up (see
PLASTER-FCN) and everything in the room falls into it. This is handled byDUMP-ALL-ON-GROUND.But this function does not check if the room just went dark, so even if your torch falls into the pit the room remains lit. If you leave and re-enter the room, it's dark as it should be.