Crash when stacking to chests.

Sorry for the how thin this initial report is, I'll update it if I can narrow the repro case.

Using version 0.0.5. and pressing the quick stack hotkey sometimes causes a lock-up and CTD.  I've only had it happen when when pressing the key more than once near storage areas with large numbers of chests.

The current repro case is stand near many chests and spam the stack hotkey.