No, the crash is genuine I think.
That last line:
*DEBUG ERROR: ***Ship (4-Fighter M5-2X 5) is in a fleet, but fleet with ID=699 not found. ***
Debug Message: ERROR: Ship says its in fleet but there are no other ships with it.
Basically here's the issue:
The AI is much MUCH MUCH better about organizing fleets. But there seem to be cases where a ship says it's in a fleet when it's not.
We need to figure this out.