[BUGFIX] Avoid undefined array key "updateReferenceIndex" in Extbase

Resolves: #98580
Releases: main, 11.5
Change-Id: Ib3ee06cb2849efd8e4cf18fc2497f3c0fed0f752
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76059


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/extbase/Classes/Persistence/Generic/Backend.php

@@ -648,7 +648,7 @@ class Backend implements BackendInterface, SingletonInterface
             $this->eventDispatcher->dispatch(new EntityAddedToPersistenceEvent($object));
         }
         $frameworkConfiguration = $this->configurationManager->getConfiguration(ConfigurationManagerInterface::CONFIGURATION_TYPE_FRAMEWORK);
-        if ($frameworkConfiguration['persistence']['updateReferenceIndex'] === '1') {
+        if (($frameworkConfiguration['persistence']['updateReferenceIndex'] ?? '') === '1') {
             $this->referenceIndex->updateRefIndexTable($dataMap->getTableName(), $uid);
         }
         $this->session->registerObject($object, $uid);
@@ -887,7 +887,7 @@ class Backend implements BackendInterface, SingletonInterface
 
         $this->removeRelatedObjects($object);
         $frameworkConfiguration = $this->configurationManager->getConfiguration(ConfigurationManagerInterface::CONFIGURATION_TYPE_FRAMEWORK);
-        if ($frameworkConfiguration['persistence']['updateReferenceIndex'] === '1') {
+        if (($frameworkConfiguration['persistence']['updateReferenceIndex'] ?? '') === '1') {
             $this->referenceIndex->updateRefIndexTable($tableName, $object->getUid());
         }
     }