Here is an easy recipe crashing APu:
1. Using the Edit button on a linked image file.
2. Switching to Photo Persona.
3. Doing the edits.
4. Closing the tab with the upright X. Save after the warning that the file is modified.
Result: APu crashes to the desktop
4. Alternative: Save the file and then close the tab.
Result: APu does not crash.
In the end I think I (probably) found the reason for the crash. Doing the recipe with the linked file located on the desktop gave no crash. But APu crashes when the linked file is located on a drive (network drive in my case) with a path that contains special characters (in my case the German Umlaut ü).