TRIAGED - sub statuses required

TRIAGED could do with some sub-statuses as there are some bugs which can be fixed easily but should be investigated more as they are evidence of something going wrong elsewhere. So perhaps sub-statuses of FIX and INVESTIGATE

For instance, there are several crashes in Stack.insertPieceAt which is being called via Stack.insertChild from Stack.setState.

A fix would be for Stack.insertPieceAt to check its parameter is valid and adjust if required which would stop the crash. But a more detailed investigation is needed. The only way I can think the crash could happen is if the same piece was on the Stack twice (unless multiple threads are running).

So perhaps rather than a fix this bug needs some code added which will report more details in an IllegalStateException so we can find the real cause of the problem