Merge pull request #8910 from nextcloud/fix-login-error

Avoid to leak a user ID that is not a string to reach a user backend

core/Controller/LoginController.php

@@ -141,7 +141,8 @@ class LoginController extends Controller {
 	 *
 	 * @return TemplateResponse|RedirectResponse
 	 */
-	public function showLoginForm($user, $redirect_url) {
+	public function showLoginForm(string $user = null, string $redirect_url = null): Http\Response {
+
 		if ($this->userSession->isLoggedIn()) {
 			return new RedirectResponse(OC_Util::getDefaultPageUrl());
 		}