change invoice action impl. changing .http sample file

media-store/app-src/src/components/tracks/Track.jsx

@@ -53,8 +53,11 @@ const Track = ({ initialTrack, isAlreadyOrdered }) => {
 };
 
 Track.propTypes = {
-  initialTrack: PropTypes.object,
+  initialTrack: PropTypes.object.isRequired,
   isAlreadyOrdered: PropTypes.bool,
 };
+Track.defaultProps = {
+  isAlreadyOrdered: undefined,
+};
 
 export { Track };