Minor changes to get rid of warnings

web/index.html

@@ -31,7 +31,7 @@
   <link rel="manifest" href="manifest.json">
   <script>
     // The value below is injected by flutter build, do not touch.
-    var serviceWorkerVersion = null;
+    var serviceWorkerVersion = '{{flutter_service_worker_version}}';
   </script>
   <!-- This script adds the flutter initialization JS code -->
   <script src="flutter.js" defer></script>
@@ -40,7 +40,7 @@
   <script>
     window.addEventListener('load', function(ev) {
       // Download main.dart.js
-      _flutter.loader.loadEntrypoint({
+      _flutter.loader.load({
         serviceWorker: {
           serviceWorkerVersion: serviceWorkerVersion,
         }