[BUGFIX] Fix broken session handling

Classes/Controller/AbstractController.php

@@ -63,7 +63,7 @@ abstract class AbstractController extends ActionController {
 	 * @param BackendUserAuthentication $backendUserAuthentication
 	 */
 	public function injectBackendUserAuthentication(BackendUserAuthentication $backendUserAuthentication): void {
-		$this->backendUserAuthentication = $backendUserAuthentication;
+		$this->backendUserAuthentication = $GLOBALS['BE_USER'];
 	}
 
 	/**
@@ -100,7 +100,7 @@ abstract class AbstractController extends ActionController {
 	 * @param $data
 	 */
 	protected function writeToSession(string $key, $data): void {
-		$this->backendUserAuthentication->setSessionData(self::sessionKey . '_' . $key, $data);
+		$this->backendUserAuthentication->setAndSaveSessionData(self::sessionKey . '_' . $key, $data);
 	}
 
 	/**