Fix var not defined

htdocs/modulebuilder/index.php

@@ -46,6 +46,9 @@ $action = GETPOST('action', 'aZ09');
 $confirm = GETPOST('confirm', 'alpha');
 $cancel = GETPOST('cancel', 'alpha');
 
+$sortfield = '';
+$sortorder = '';
+
 $module = GETPOST('module', 'alpha');
 $tab = GETPOST('tab', 'aZ09');
 $tabobj = GETPOST('tabobj', 'alpha');