Update Service Worker and Favicon (#3142)

* Update favicon

* Update ServiceWorker with error logging

app/assets/javascripts/serviceworker.js.erb

@@ -1,4 +1,4 @@
-var CACHE_VERSION = 'v2.7.0';
+var CACHE_VERSION = 'v2.7.1';
 var CACHE_NAME = CACHE_VERSION + ':sw-cache::';
 var REQUESTS_LIMIT = 40;
 
@@ -49,7 +49,8 @@ function onFetch(event) {
       }
       return fetch(event.request)
         .then(fetchedFromNetwork)
-        .catch(function fallback() {
+        .catch(function fallback(err) {
+           console.log(err)
            return cached || caches.match('/offline.html');
          })
       }
@@ -115,7 +116,7 @@ function onPush(event) {
   var title = 'DEV Connect 👋 ';
   var body = event.data.text();
   var icon = '<%= image_path "devlogo-pwa-128.png" %>';
-  var tag = 'default-tag' + body;  
+  var tag = 'default-tag' + body;
   event.waitUntil(
     self.registration.showNotification(title, {
       body: body,