[BUGFIX] Check if language is accessible in PageContentErrorHandler

The changes made in #90135 introduced a regression, that made the
PageContentErrorHandler ignore the enabled flag of the requested
language.

Resolves: #91013
Related: #90135
Related: #87865
Releases: master, 9.5
Change-Id: I23504caab2f060c49f112d7bc529e71d02939486
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64131


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>

typo3/sysext/core/Classes/Error/PageErrorHandler/PageContentErrorHandler.php

@@ -120,7 +120,7 @@ class PageContentErrorHandler implements PageErrorHandlerInterface
         /** @var SiteLanguage $requestLanguage */
         $requestLanguage = $request->getAttribute('language', null);
         // Try to get the current request language from the site that was found above
-        if ($requestLanguage instanceof SiteLanguage) {
+        if ($requestLanguage instanceof SiteLanguage && $requestLanguage->isEnabled()) {
             try {
                 $language = $site->getLanguageById($requestLanguage->getLanguageId());
             } catch (\InvalidArgumentException $e) {