[BUGFIX] Prevent exception in ImageCropUpdater

The ImageCropUpdater throws an exception if a non-existing file is tried
to be processed. This happens because deleted rows are updated. The patch
checks the returned file object before further processing is executed.

Resolves: #81470
Releases: master, 8.7
Change-Id: I488994b1ad842e28d928f3b4a2db1c8c007afe3c
Reviewed-on: https://review.typo3.org/53120


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Helmut Hummel <typo3@helhum.io>
Tested-by: Helmut Hummel <typo3@helhum.io>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>