Merge pull request #905 from nextcloud/fix/904/default-redirecturl

fix(Controller): make redirectUrl optional

Author: blizzz

lib/Controller/SAMLController.php

@@ -539,7 +539,7 @@ public function genericError(string $message): Http\TemplateResponse {
 	 * @NoCSRFRequired
 	 * @OnlyUnauthenticatedUsers
 	 */
-	public function selectUserBackEnd(string $redirectUrl): Http\TemplateResponse {
+	public function selectUserBackEnd(string $redirectUrl = ''): Http\TemplateResponse {
 		$attributes = ['loginUrls' => []];
 
 		if ($this->samlSettings->allowMultipleUserBackEnds()) {