old_contents: /**
   * The cache name
   * @type {String}
   */
  const cacheName = 'v6';
  
  /**
   * Things to cache
   * @type {Array}
   */
  const catCache = [
    '/service-worker/',
    '/service-worker/index.html',
    '/service-worker/manifest.json',
    '/service-worker/logo.png',
    '/service-worker/static/images/cat1.jpg',
    '/service-worker/static/images/cat2.jpg',
    '/service-worker/static/images/cat3.jpg',
    '/service-worker/static/images/cat4.jpg'
  ];
  
  this.oninstall = (event) => {
    event.waitUntil(
      caches.open(cacheName)
        .then((cache) => {
          return cache.addAll(catCache);
        })
    );
  };
  
  this.onfetch = (event) => {
    event.respondWith(
      caches.match(event.request)
        .then(response => {
          if (response) {
            return response;
          }
  
          return fetch(event.request)
            .then((res) => {
              const r = res.clone();
              caches.open(CACHE_NAME)
                .then((cache) => {
                  cache.put(event.request, r);
              });
            return res; // Don't wait for the request to cache
            });
        })
    );
  };
  
  
new_contents: /**
   * The cache name
   * @type {String}
   */
  const CACHE_NAME = 'v7';
  
  /**
   * Things to cache
   * @type {Array}
   */
  const catCache = [
    '/service-worker/',
    '/service-worker/index.html',
    '/service-worker/manifest.json',
    '/service-worker/logo.png',
    '/service-worker/static/images/cat1.jpg',
    '/service-worker/static/images/cat2.jpg',
    '/service-worker/static/images/cat3.jpg',
    '/service-worker/static/images/cat4.jpg'
  ];
  
  this.oninstall = (event) => {
    event.waitUntil(
      caches.open(CACHE_NAME)
        .then((cache) => {
          return cache.addAll(catCache);
        })
    );
  };
  
  this.onfetch = (event) => {
    event.respondWith(
      caches.open(CACHE_NAME)
      .then(caches.match(event.request)
        .then(response => {
          if (response) {
            return response;
          }
  
          return fetch(event.request)
            .then((res) => {
              const r = res.clone();
              caches.open(CACHE_NAME)
                .then((cache) => {
                  cache.put(event.request, r);
              });
            return res; // Don't wait for the request to cache
            });
        })
      )
    );
  };
  
  
subject: fix silly error