fix(service-worker): Install service worker correctly (#222)

* fix(service-worker): register service worker immediately

src/serviceWorkerRegistration.js

@@ -31,26 +31,24 @@ export function register(config) {
       return
     }
 
-    window.addEventListener('load', () => {
-      const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`
+    const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`
 
-      if (isLocalhost) {
-        // This is running on localhost. Let's check if a service worker still exists or not.
-        checkValidServiceWorker(swUrl, config)
+    if (isLocalhost) {
+      // This is running on localhost. Let's check if a service worker still exists or not.
+      checkValidServiceWorker(swUrl, config)
 
-        // Add some additional logging to localhost, pointing developers to the
-        // service worker/PWA documentation.
-        navigator.serviceWorker.ready.then(() => {
-          console.log(
-            'This web app is being served cache-first by a service ' +
-              'worker. To learn more, visit https://cra.link/PWA'
-          )
-        })
-      } else {
-        // Is not localhost. Just register service worker
-        registerValidSW(swUrl, config)
-      }
-    })
+      // Add some additional logging to localhost, pointing developers to the
+      // service worker/PWA documentation.
+      navigator.serviceWorker.ready.then(() => {
+        console.log(
+          'This web app is being served cache-first by a service ' +
+            'worker. To learn more, visit https://cra.link/PWA'
+        )
+      })
+    } else {
+      // Is not localhost. Just register service worker
+      registerValidSW(swUrl, config)
+    }
   }
 }