$.load should handle error case

[dixonsiu]

Currently it is assumed that it always return successfully. But sometimes, when it fails, the spinner does not stop.

Example for how to handle error.

    <script>
    $( "#success" ).load( "/not-here.php", function( response, status, xhr ) {
      if ( status == "error" ) {
        var msg = "Sorry but there was an error: ";
        $( "#error" ).html( msg + xhr.status + " " + xhr.statusText );
      }
    });
    </script>