[TASK] Replace deprecated language constant

Classes/Service/ConfigurationService.php

@@ -75,6 +75,7 @@ class ConfigurationService extends AbstractService {
 	 * Note that the default value will be set, if a option check fails.
 	 *
 	 * @return array
+	 * @throws \InvalidArgumentException
 	 */
 	public function prepareConfig() {
 		if (!empty($this->extConfig)) {
@@ -127,9 +128,9 @@ class ConfigurationService extends AbstractService {
 			unset($this->extConfig['viewLanguages']);
 
 			$availableLanguageKeys = [];
-			$languages = explode(
-				'|', TYPO3_languages
-			);
+			$locales = GeneralUtility::makeInstance(ObjectManager::class)->get(Locales::class);
+			$languages = $locales->getLocales();
+
 			foreach ($languages as $language) {
 				$availableLanguageKeys[$language] = TRUE;
 			}
@@ -143,7 +144,7 @@ class ConfigurationService extends AbstractService {
 					}
 				}
 
-				if ($lang != 'default') {
+				if ($lang !== 'default') {
 					$this->extConfig['viewLanguages'][] = $lang;
 				}
 			}