Merge pull request #8693 from nextcloud/13-8173

[stable13] Fix undefined index problem

Author: rullzer

lib/private/AppConfig.php

@@ -293,9 +293,11 @@ public function getValues($app, $key) {
 	public function getFilteredValues($app) {
 		$values = $this->getValues($app, false);
 
-		foreach ($this->sensitiveValues[$app] as $sensitiveKey) {
-			if (isset($values[$sensitiveKey])) {
-				$values[$sensitiveKey] = IConfig::SENSITIVE_VALUE;
+		if (array_key_exists($app, $this->sensitiveValues)) {
+			foreach ($this->sensitiveValues[$app] as $sensitiveKey) {
+				if (isset($values[$sensitiveKey])) {
+					$values[$sensitiveKey] = IConfig::SENSITIVE_VALUE;
+				}
 			}
 		}