[BUGFIX] Fix warning in TypoScriptParser

The method getVal now always returns an array with
a string at index 0 and an array at index 1.

Resolves: #96001
Releases: master, 11.5
Change-Id: Ia1b321694767fa01b1de9176b87470522511d150
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72311


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>