Ticket #13634: no-menu-widget-fallback.13634.diff

wp-includes/default-widgets.php

@@ -1072 +1072 @@
                 if ( !empty($instance['title']) )
                         echo $args['before_title'] . $instance['title'] . $args['after_title'];
 
-                wp_nav_menu( array( 'menu' => $nav_menu ) );
+                wp_nav_menu( array( 'fallback_cb' => '', 'menu' => $nav_menu ) );
 
                 echo $args['after_widget'];
         }