fixes no offline fallback page bug

schoolapps/static/common/serviceworker.js

@@ -134,7 +134,7 @@ function networkFirstFetch(event) {
 function fromCache(request) {
   // Check to see if you have it in the cache
   // Return response
-  // If not in the cache, then return error page
+  // If not in the cache, then return offline fallback page
   return caches.open(CACHE).then(function (cache) {
     return cache.match(request).then(function (matching) {
       if (!matching || matching.status === 404) {