For empty storages, we need to avoid accessing inexistent array elements.

Resolves: #97417
Relates: #97554
Releases: main, 11.5
Change-Id: Ieee36b4c0ede9726ce936030f631a3322e3813a9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74765


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>