PHP 5.3 issue - Attempt to modify property of non-object (Mailing Labelmodule)

warning: Attempt to modify property of non-object in [...]/sites/all/modules/contrib/mailing_label/mailing_label_plugin_display_attachment.inc on line 20.

It happens when you are doing update.php. A similar problem happens ini http://drupal.org/node/549884. By using the same method ini http://drupal.org/node/549884#comment-2577586, the code should be modified become:

  function options(&$display) {
    parent::options($display);
    if ( is_object($display) ) {
      $display->display_options['items_per_page'] = 0;
      $display->display_options['row_plugin'] = '';
      $display->display_options['defaults']['style_options'] = FALSE;
      $display->display_options['defaults']['items_per_page'] = FALSE;
      $display->display_options['defaults']['row_plugin'] = FALSE;
      $display->display_options['defaults']['row_options'] = FALSE;
    } else {
      $display['display_options']['items_per_page'] = 0;
      $display['display_options']['row_plugin'] = '';
      $display['display_options']['defaults']['style_options'] = FALSE;
      $display['display_options']['defaults']['items_per_page'] = FALSE;
      $display['display_options']['defaults']['row_plugin'] = FALSE;
      $display['display_options']['defaults']['row_options'] = FALSE;
    }
  }