feat(gatsby-plugin-offline): reload when missing resources and SW was updated + add "onServiceWorkerUpdateReady" API

packages/gatsby-plugin-offline/sw-append.js

@@ -12,22 +12,7 @@ const navigationRoute = new workbox.routing.NavigationRoute(({ event }) => {
       const offlineShell = `%pathPrefix%/offline-plugin-app-shell-fallback/index.html`
       const cacheName = workbox.core.cacheNames.precache
 
-      return caches.match(offlineShell, { cacheName }).then(cachedResponse => {
-        if (!cachedResponse) {
-          return fetch(offlineShell).then(response => {
-            if (response.ok) {
-              return caches.open(cacheName).then(cache =>
-                // Clone is needed because put() consumes the response body.
-                cache.put(offlineShell, response.clone()).then(() => response)
-              )
-            } else {
-              return fetch(event.request)
-            }
-          })
-        }
-
-        return cachedResponse
-      })
+      return caches.match(offlineShell, { cacheName })
     }
 
     return fetch(event.request)

packages/gatsby/cache-dir/ensure-resources.js

@@ -129,6 +129,8 @@ class EnsureResources extends React.Component {
 
   render() {
     if (!this.hasResources(this.state.pageResources) && isInitialRender) {
+      window.___failedResources = true
+
       // prevent hydrating
       throw new Error(`Missing resources for ${this.state.location.pathname}`)
     }

packages/gatsby/cache-dir/register-service-worker.js

@@ -25,6 +25,12 @@ if (
                 // have been added to the cache.
                 // We call the onServiceWorkerUpdateReady API so users can show update prompts.
                 apiRunner(`onServiceWorkerUpdateReady`, { serviceWorker: reg })
+
+                // If resources failed for the current page, reload.
+                if (window.___failedResources) {
+                  console.log(`resources failed, SW updated - reloading`)
+                  window.reload()
+                }
               } else {
                 // At this point, everything has been precached.
                 // It's the perfect time to display a "Content is cached for offline use." message.