fix(router): throw a better error message when angular 1 is not bootstraped

modules/@angular/router/upgrade.ts

@@ -40,10 +40,20 @@ export const RouterUpgradeInitializer = {
   deps: [UpgradeModule, ApplicationRef, RouterPreloader, ROUTER_CONFIGURATION]
 };
 
+/**
+ * @internal
+ */
 export function initialRouterNavigation(
     ngUpgrade: UpgradeModule, ref: ApplicationRef, preloader: RouterPreloader,
     opts: ExtraOptions): Function {
   return () => {
+    if (!ngUpgrade.$injector) {
+      throw new Error(`
+        RouterUpgradeInitializer can be used only after UpgradeModule.bootstrap has been called.
+        Remove RouterUpgradeInitializer and call setUpLocationSync after UpgradeModule.bootstrap.
+      `);
+    }
+
     const router = ngUpgrade.injector.get(Router);
     const ref = ngUpgrade.injector.get(ApplicationRef);
 
@@ -52,17 +62,28 @@ export function initialRouterNavigation(
     if (opts.initialNavigation === false) {
       router.setUpLocationChangeListener();
     } else {
-      setTimeout(() => { router.initialNavigation(); }, 0);
+      router.initialNavigation();
     }
 
-    // History.pushState does not fire onPopState, so the angular2 location
-    // doesn't detect it. The workaround is to attach a location change listener
-    // that will call navigate directly.
-    ngUpgrade.$injector.get('$rootScope')
-        .$on('$locationChangeStart', (_: any, next: string, __: string) => {
-          const url = document.createElement('a');
-          url.href = next;
-          router.navigateByUrl(url.pathname);
-        });
+    setUpLocationSync(ngUpgrade);
   };
+}
+
+/**
+ * @whatItDoes Sets up a location synchronization.
+ *
+ * History.pushState does not fire onPopState, so the angular2 location
+ * doesn't detect it. The workaround is to attach a location change listener
+ *
+ * @experimental
+ */
+export function setUpLocationSync(ngUpgrade: UpgradeModule): void {
+  const router: Router = ngUpgrade.injector.get(Router);
+  const url = document.createElement('a');
+
+  ngUpgrade.$injector.get('$rootScope')
+      .$on('$locationChangeStart', (_: any, next: string, __: string) => {
+        url.href = next;
+        router.navigateByUrl(url.pathname);
+      });
 }