Merge pull request #23895 from nextcloud/backport/23799/stable19-minimal

[stable19] fix potentially passing null to events where IUser is expected

apps/user_ldap/lib/Jobs/UpdateGroups.php

@@ -47,6 +47,7 @@
 use OCP\Group\Events\UserAddedEvent;
 use OCP\Group\Events\UserRemovedEvent;
 use OCP\ILogger;
+use OCP\IUser;
 
 class UpdateGroups extends \OC\BackgroundJob\TimedJob {
 	private static $groupsFromDB;
@@ -116,15 +117,19 @@ private static function handleKnownGroups($groups) {
 			$groupObject = $groupManager->get($group);
 			foreach (array_diff($knownUsers, $actualUsers) as $removedUser) {
 				$userObject = $userManager->get($removedUser);
-				$dispatcher->dispatchTyped(new UserRemovedEvent($groupObject, $userObject));
+				if ($userObject instanceof IUser) {
+					$dispatcher->dispatchTyped(new UserRemovedEvent($groupObject, $userObject));
+				}
 				\OCP\Util::writeLog('user_ldap',
 				'bgJ "updateGroups" – "'.$removedUser.'" removed from "'.$group.'".',
 					ILogger::INFO);
 				$hasChanged = true;
 			}
 			foreach (array_diff($actualUsers, $knownUsers) as $addedUser) {
 				$userObject = $userManager->get($addedUser);
-				$dispatcher->dispatchTyped(new UserAddedEvent($groupObject, $userObject));
+				if ($userObject instanceof IUser) {
+					$dispatcher->dispatchTyped(new UserAddedEvent($groupObject, $userObject));
+				}
 				\OCP\Util::writeLog('user_ldap',
 				'bgJ "updateGroups" – "'.$addedUser.'" added to "'.$group.'".',
 					ILogger::INFO);