Fixed exception thrown when logging in as an LDAP user due to a direc…

…tory not having password policy attributes available.

nextcloud#33622

Signed-off-by: Adam Reece <adam@reece.wales>

apps/user_ldap/lib/User/User.php

@@ -664,11 +664,15 @@ public function handlePasswordExpiry($params) {
 			//retrieve relevant password policy attributes
 			$cacheKey = 'ppolicyAttributes' . $ppolicyDN;
 			$result = $this->connection->getFromCache($cacheKey);
-			if (is_null($result)) {
+			if (is_null($result) || !is_array($result) || empty($result[0]) || !is_array($result[0])) {
 				$result = $this->access->search('objectclass=*', $ppolicyDN, ['pwdgraceauthnlimit', 'pwdmaxage', 'pwdexpirewarning']);
 				$this->connection->writeToCache($cacheKey, $result);
 			}
 
+			if (is_null($result) || !is_array($result) || empty($result[0]) || !is_array($result[0])) {
+				return;//password policy attributes not found in directory
+			}
+
 			$pwdGraceAuthNLimit = array_key_exists('pwdgraceauthnlimit', $result[0]) ? $result[0]['pwdgraceauthnlimit'] : [];
 			$pwdMaxAge = array_key_exists('pwdmaxage', $result[0]) ? $result[0]['pwdmaxage'] : [];
 			$pwdExpireWarning = array_key_exists('pwdexpirewarning', $result[0]) ? $result[0]['pwdexpirewarning'] : [];