[BUGFIX] Avoid undefined array keys in Indexer

Resolves: #99151
Releases: main, 11.5
Change-Id: Ibddea0cd6b4f869632899b7887f573bb7a6856b8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76758


Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>