[BUGFIX] Fix phpstan errors from ReturnTypeRule

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Resolves: #94264
Releases: master
Change-Id: I0799fce1f3f316a4b6e0925f6813738a2c53f8a9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69394


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>