Catch an null given error

Author: robin.kluth

src/LdapAuth.php

@@ -378,7 +378,10 @@ public function searchUser(string $searchFor, $attributes = "", $searchFilter =
                 ]);
                 if (!$result) {
                     // Something is wrong with the search query
-                    Yii::warning('ldap_search_error: ' . ldap_error($this->_l));
+                    if (is_null($this->_l)) {
+                        Yii::warning('ldap_search_error: null', __FUNCTION__);
+                    }
+                    Yii::warning('ldap_search_error: ' . ldap_error($this->_l), __FUNCTION__);
                     break;
                 }
                 ldap_parse_result($this->_l, $result, $errcode, $matcheddn, $errmsg, $referrals, $controls);