Game crashes and then crashes again after restart and reload of saved game.

Recovered from backup, it may be treasure maps obtained when breaking chests containing them.

Log: https://paste.ee/p/1PqLt
Crash report: https://paste.ee/p/TVPCW

It appears that, somehow, the map data is trying to load nonexistent chunks.

Is there a particular reason we're not using ItemMap.setupNewMap?

cc41f76