[TASK] Prevent notice in InstallStatusReport

Add isset check before use is_array.
This will prevent a notice if the
array key does not exist.

Resolves: #86187
Releases: master
Change-Id: I6f74f2200981802ffe2d9ca527ed7230c0d75b27
Reviewed-on: https://review.typo3.org/58215


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Jörg Bösche <typo3@joergboesche.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>