Meanwhile I have narrowed down the steps to reproduce a bit:
1. Open StarUML (will start with a new file)
2. Save the new file
3. Wait about 10 minutes (in the dev console it will print something about AutoBackup at that point)
4. In StarUML click "File -> New". This will trigger the crash
I'm not sure why the backup plays a role here (if I create the new file before the backup is created (if I wait less than 10 minutes), it does not happen).
I was digging a bit through the code in the dev console and set a breakpoint in the handleNew function, but it does not even reach that far and seems to crash before