How to check if Google Street View available and display message?

HTML

<script src="http://maps.googleapis.com/maps/api/js?libraries=places,drawing&amp;sensor=false"></script>
<div id="pano" style="width: 100%; height: 100%;float:left"></div>

CSS

html, body, #map-canvas {
      height: 100%;
      margin: 0px;
      padding: 0px
  }
  #pano {
      margin-top:5%;
  }
}

JavaScript

/*
 * Click the map to set a new location for the Street View camera.
 */
var map;
var berkeley = new google.maps.LatLng(23.028397, 72.50676199999998);
var sv = new google.maps.StreetViewService();

var panorama;

function initialize() {

    panorama = new google.maps.StreetViewPanorama(document.getElementById('pano'));

    // Set the initial Street View camera to the center of the map
    sv.getPanoramaByLocation(berkeley, 50, processSVData);

    // Look for a nearby Street View panorama when the map is clicked.
    // getPanoramaByLocation will return the nearest pano when the
    // given radius is 50 meters or less.
    google.maps.event.addListener(map, 'click', function (event) {
        sv.getPanoramaByLocation(event.latLng, 50, processSVData);
    });
}

function processSVData(data, status) {
    if (status == google.maps.StreetViewStatus.OK) {
        var marker = new google.maps.Marker({
            position: data.location.latLng,
            map: map,
            title: data.location.description
        });

        panorama.setPano(data.location.pano);
        panorama.setPov({
            heading: 270,
            pitch: 0
        });
        panorama.setVisible(true);

        google.maps.event.addListener(marker, 'click', function () {

            var markerPanoID = data.location.pano;
            // Set the Pano to use the passed panoID
            panorama.setPano(markerPanoID);
            panorama.setPov({
                heading: 270,
                pitch: 0
            });
            panorama.setVisible(true);
        });
    } else {
        alert('Street View data not found for this location.');
    }
}

initialize();