[BUGFIX] Fix editing image in workspaces

Return value of getWorkspaceVersionOfRecord changed to null.
Adjust the check to catch null as well.

Resolves: #77735
Releases: master
Change-Id: I6e68e377baba2bde08bd10faac1daee855913572
Reviewed-on: https://review.typo3.org/49713


Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Bamboo TYPO3com <info@typo3.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>