[BUGFIX] Fix identification for logged in frontend users

Because TSFE->fe_user was dropped in TYPO3 13, FE user identification was not possible (without error).
See https://docs.typo3.org/c/typo3/cms-core/main/en-us/Changelog/13.0/Breaking-102605-TSFE-fe_userRemoved.html for details

Classes/Domain/Tracker/FrontenduserAuthenticationTracker.php

@@ -28,7 +28,7 @@ public function trackByFrontenduserAuthentication(): void
         if (FrontendUtility::isLoggedInFrontendUser()) {
             $userRepository = GeneralUtility::makeInstance(FrontendUserRepository::class);
             /** @var FrontendUser $user */
-            $user = $userRepository->findByUid((int)FrontendUtility::getPropertyFromLoggedInFrontendUser('uid'));
+            $user = $userRepository->findByUid((int)FrontendUtility::getPropertyFromLoggedInFrontendUser());
 
             $this->setRelationToFrontendUser($user);
             $this->addEmailAttribute($user);

Classes/Utility/FrontendUtility.php

@@ -5,6 +5,7 @@
 
 use In2code\Lux\Domain\Service\SiteService;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Frontend\Authentication\FrontendUserAuthentication;
 use TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController;
 
 class FrontendUtility
@@ -43,18 +44,27 @@ public static function getCurrentHostAndDomain(): string
 
     public static function isLoggedInFrontendUser(): bool
     {
-        return !empty(self::getTyposcriptFrontendController()->fe_user->user['uid']);
+        $authentication = self::getFrontendUserAuthentication();
+        if ($authentication !== null) {
+            return $authentication->user['uid'] > 0;
+        }
+        return false;
     }
 
     public static function getPropertyFromLoggedInFrontendUser($propertyName = 'uid'): string
     {
-        $tsfe = self::getTyposcriptFrontendController();
-        if (!empty($tsfe->fe_user->user[$propertyName])) {
-            return (string)$tsfe->fe_user->user[$propertyName];
+        $authentication = self::getFrontendUserAuthentication();
+        if ($authentication !== null) {
+            return (string)($authentication->user[$propertyName] ?? '');
         }
         return '';
     }
 
+    protected static function getFrontendUserAuthentication(): ?FrontendUserAuthentication
+    {
+        return $GLOBALS['TYPO3_REQUEST']?->getAttribute('frontend.user');
+    }
+
     /**
      * @return ?TypoScriptFrontendController
      * @SuppressWarnings(PHPMD.Superglobals)