[BUGFIX] Fatal in ext:form using LanguageServiceFactory

Patch #94414 broke a case in ext:form leading to a
fatal, easily reproducible when opening a content
element having a form.
The class is internal and only used in backend
through a hook and can thus rely on GLOBALS['LANG']
like so many other backend classes do.

Resolves: #94429
Related: #94414
Releases: master
Change-Id: I578d3b1d61894c210bb0fb20cddf44307cb40ae2
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69653
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Jochen <rothjochen@gmail.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Jochen <rothjochen@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/form/Classes/Domain/Configuration/FlexformConfiguration/Processors/FinisherOptionGenerator.php

@@ -17,10 +17,9 @@
 
 namespace TYPO3\CMS\Form\Domain\Configuration\FlexformConfiguration\Processors;
 
-use TYPO3\CMS\Core\Localization\LanguageServiceFactory;
+use TYPO3\CMS\Core\Localization\LanguageService;
 use TYPO3\CMS\Core\Utility\ArrayUtility;
 use TYPO3\CMS\Core\Utility\Exception\MissingArrayPathException;
-use TYPO3\CMS\Core\Utility\GeneralUtility;
 
 /**
  * Generate a FlexForm element for a finisher option
@@ -29,22 +28,6 @@
  */
 class FinisherOptionGenerator extends AbstractProcessor
 {
-    /**
-     * @var \TYPO3\CMS\Core\Localization\LanguageServiceFactory
-     */
-    protected $languageService;
-
-    /**
-     * @param ProcessorDto $converterDto
-     */
-    public function __construct(ProcessorDto $converterDto)
-    {
-        parent::__construct($converterDto);
-
-        $this->languageService = GeneralUtility::makeInstance(LanguageServiceFactory::class);
-        $this->languageService->includeLLFile('EXT:form/Resources/Private/Language/Database.xlf');
-    }
-
     /**
      * @param string $_ unused in this context
      * @param mixed $__ unused in this context
@@ -89,10 +72,11 @@ public function __invoke(string $_, $__, array $matches)
         } catch (MissingArrayPathException $exception) {
         }
 
+        $languageService = $this->getLanguageService();
         if (empty($optionValue)) {
-            $elementConfiguration['label'] .= sprintf(' (%s: "%s")', $this->languageService->getLL('default'), $this->languageService->getLL('empty'));
+            $elementConfiguration['label'] .= sprintf(' (%s: "%s")', $languageService->getLL('default'), $languageService->getLL('empty'));
         } else {
-            $elementConfiguration['label'] .= sprintf(' (%s: "' . $optionValue . '")', $this->languageService->getLL('default'));
+            $elementConfiguration['label'] .= sprintf(' (%s: "' . $optionValue . '")', $languageService->getLL('default'));
         }
 
         if (isset($elementConfiguration['config'])) {
@@ -104,4 +88,9 @@ public function __invoke(string $_, $__, array $matches)
 
         $this->converterDto->setResult($sheetElements);
     }
+
+    protected function getLanguageService(): LanguageService
+    {
+        return $GLOBALS['LANG'];
+    }
 }