[BUGFIX] AdminPanelView tries to count null value

Resolves: #83345
Releases: master, 8.7, 7.6
Change-Id: I49e0de26154430c8a93c6a25a7fa54d5e49be39d
Reviewed-on: https://review.typo3.org/55102


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Alexander Opitz <opitz.alexander@googlemail.com>
Tested-by: Alexander Opitz <opitz.alexander@googlemail.com>