fix(ldapfield): missing error message

Author: btry

inc/field/ldapselectfield.class.php

@@ -151,6 +151,7 @@ public function prepareQuestionInputForSave($input) {
       if (isset($ldap_values['ldap_attribute'])) {
          $ldap_dropdown = RuleRightParameter::getById((int) $ldap_values['ldap_attribute']);
          if (!($ldap_dropdown instanceof RuleRightParameter)) {
+            Session::addMessageAfterRedirect(__('LDAP attribute is required!', 'formcreator'), false, ERROR);
             return [];
          }
       }