Merge pull request #2421 from nextcloud/backport/2420/stable32

[stable32] fix: array offset error if value is not set

Author: miaulalala

lib/Consumer.php

@@ -95,7 +95,7 @@ public function bulkReceive(IEvent $event, array $affectedUserIds, ISetting $set
 				continue;
 			}
 			$event->setAffectedUser($affectedUser);
-			$notificationSetting = $userPushSettings[$affectedUser];
+			$notificationSetting = $userPushSettings[$affectedUser] ?? null;
 			if ($notificationSetting !== null) {
 				$notificationSetting = (bool)$notificationSetting;
 			}