set $msg argument of loadHelper() default to true.

lib/plugins/syntax.php

@@ -287,7 +287,7 @@ class DokuWiki_Syntax_Plugin extends Doku_Parser_Mode {
      *
      * @return  object  helper plugin object
      */
-    function loadHelper($name, $msg) {
+    function loadHelper($name, $msg = true) {
         if(!plugin_isdisabled($name)) {
             $obj = plugin_load('helper', $name);
         } else {