[BUGFIX] Avoid undefined array key in ContentObjectRenderer::parseFuncInternal

Resolves: #99154
Releases: main, 11.5
Change-Id: Iff01454dffb3afc0ebd4dff440467c0170d05934
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76776


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