Bug in javascript on ajax refresh

When I use shoutbox with periodic refresh, each time the refresh comes I see the error in firebug.

This is in shoutbox-form.js:

        $.each(Drupal.shoutbox.afterPost, function (func) {
          if ($.isFunction(this.execute)) {
            this.execute();
          }
        });

Beacause the Drupal.shoutbox.afterPost is undefined.

My fix is:

      if (Drupal.shoutbox.afterPost)
        $.each(Drupal.shoutbox.afterPost, function (func) {
          if ($.isFunction(this.execute)) {
            this.execute();
          }
        });