[BUGFIX] Initialize the localRootLine property before usage

This change ensures that the root line is initialized before being accessed on TSFE initialization.

Fixes: #4287
Ports: #4423

Author: davidlemaitre

Classes/FrontendEnvironment/Tsfe.php

@@ -36,6 +36,7 @@
 use TYPO3\CMS\Core\SingletonInterface;
 use TYPO3\CMS\Core\Site\SiteFinder;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Core\Utility\RootlineUtility;
 use TYPO3\CMS\Frontend\Authentication\FrontendUserAuthentication;
 use TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController;
 use TYPO3\CMS\Frontend\Page\PageInformation;
@@ -111,6 +112,10 @@ protected function initializeTsfe(int $pageId, int $language = 0, ?int $rootPage
         $pageInformation->setId($pageId);
         $pageInformation->setPageRecord(BackendUtility::getRecord('pages', $pageId));
         $pageInformation->setContentFromPid($pageId);
+
+        $rootLine = GeneralUtility::makeInstance(RootlineUtility::class, $pageId)->get();
+        $pageInformation->setLocalRootLine($rootLine);
+
         $serverRequest = $this->serverRequestCache[$cacheIdentifier] ?? null;
         $pageArguments = GeneralUtility::makeInstance(PageArguments::class, $pageId, '0', []);
         if (!isset($this->serverRequestCache[$cacheIdentifier])) {