[BUGFIX] Fix PHP 8 array access in BackendUtility

When the TCA colon feature for ['ctrl']['type'] is
used in inline parent child relations, the target
record may not yet be persisted and getRecord()
returns null.

This triggers a PHP 8 array warning.
Sanitize this access.

Resolves: #97985
Releases: main, 11.5
Change-Id: If26e7aecdfc9504fbf1727813bc825de6522b9f9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75217


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