This was a long running bug with merc based muds. The logic was to scan the room items first which cased the bug. Later versions would scan corpses first, then self, then room.

Should have done it the other way around

Much better to have the world disappear from the bag.

put bag in bag of "things which do not contain itself"

Russell's Paradox: https://en.m.wikipedia.org/wiki/Russell%27s_paradox