Properly cache requests using service workers

fix service workers causing problems

remove uninstalling of service workers

add redirect: follow

Handle response.redirected correctly

instead of returning response, fulfill the original request

app/javascript/mastodon/service_worker/entry.js

@@ -24,10 +24,19 @@ self.addEventListener('fetch', function(event) {
   const url = new URL(event.request.url);
 
   if (url.pathname.startsWith('/web')) {
+    // we always make /web/login go through
+    if (url.pathname.startsWith('/web/login')) {
+      return;
+    }
     const asyncResponse = fetchRoot();
     const asyncCache = openWebCache();
 
     event.respondWith(asyncResponse.then(async response => {
+      // response was redirected - let's actually do the request from the event
+      // and return its response
+      if (response.redirected || response.type === 'opaqueredirect') {
+        return await fetch(event.request);
+      }
       if (response.ok) {
         const cache = await asyncCache;
         await cache.put('/web', response);
@@ -48,6 +57,7 @@ self.addEventListener('fetch', function(event) {
 
       return response;
     }));
+
   } else if (process.env.CDN_HOST ? url.host === process.env.CDN_HOST : url.pathname.startsWith('/system/')) {
     event.respondWith(openSystemCache().then(async cache => {
       const cached = await cache.match(event.request.url);