I gathered gold from the dungeon (down to the second level), killed some zombies, then left without the amulet. Once I left the dungeon (stood on the exit dungeon square), the game froze, and the console reported this error:
Exception in thread "main" java.lang.NullPointerException
at Game.CommandExecutor.a(Unknown Source)
at Entity.Door.l(Unknown Source)
at Entity.Door.a(Unknown Source)
at Game.EntityManager.d(Unknown Source)
at Game.PlayInstance.v(Unknown Source)
at Game.PlayInstance.a(Unknown Source)
at Achoum.Main.o(Unknown Source)
at Achoum.Main.p(Unknown Source)
at Achoum.Main.C(Unknown Source)
at Achoum.LocalLuncher.a(Unknown Source)
at Achoum.LocalLuncher.main(Unknown Source)
Exception in thread "main" java.lang.NullPointerException
at Game.CommandExecutor.a(Unknown Source)
at Entity.Door.l(Unknown Source)
at Entity.Door.a(Unknown Source)
at Game.EntityManager.d(Unknown Source)
at Game.PlayInstance.v(Unknown Source)
at Game.PlayInstance.a(Unknown Source)
at Achoum.Main.o(Unknown Source)
at Achoum.Main.p(Unknown Source)
at Achoum.Main.C(Unknown Source)
at Achoum.LocalLuncher.a(Unknown Source)
at Achoum.LocalLuncher.main(Unknown Source)