Show error message if problems parsing/loading JSON data

				status( 'Generating map...' );

				try {

					locations = JSON.parse( e.target.result ).locations;

					if ( !locations || locations.length === 0 ) {

						throw new ReferenceError( 'No location data found.' );

					}

				} catch ( ex ) {

					status( 'Something went wrong generating your map. Ensure you\'re uploading a Google Takeout JSON file that contains location data and try again, or create an issue on GitHub if the problem persists. (error: ' + ex.message + ')' );

					return;

				}

				heat._latlngs = locations.map( function ( location ) {

					return [ location.latitudeE7 * SCALAR_E7, location.longitudeE7 * SCALAR_E7 ];