[BUGFIX] Debug exception handler: set exit code on CLI

Sets the exit code to 1 when an exception is caught by the debug exception
handler, so that the error state can be checked automatically.

Change-Id: Ic89a79f2ded0b4b9ccc58a4789d9416f260fd88a
Fixes: #44118
Releases: 6.2, 6.1, 6.0
Reviewed-on: https://review.typo3.org/22630
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind