fix(platform-server): surface errors during rendering (#50587)

Prior to this change in some cases errors tht happen during routing were not being surfaced. This is due to the fact that the router has floating promises, and the platform was being destroyed prior to these being settled.

PR Close #50587

integration/platform-server/projects/ngmodule/prerender.ts

@@ -0,0 +1,43 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+/* tslint:disable:no-console  */
+import 'zone.js/node';
+import {join} from 'path';
+import {renderModule} from '@angular/platform-server';
+import {readFileSync} from 'fs';
+import {AppServerModule} from './src/main.server';
+
+const distFolder = join(process.cwd(), 'dist/ngmodule/browser');
+const indexHtml = readFileSync(join(distFolder, 'index.html'), 'utf-8');
+
+async function runTest() {
+  // Test and validate the errors are printed in the console.
+  const originalConsoleError = console.error;
+  const errors: string[] = [];
+  console.error = (error, data) => errors.push(error.toString() + ' ' + data.toString());
+
+  try {
+    await renderModule(AppServerModule, {
+      document: indexHtml,
+      url: '/error',
+    });
+  } catch {}
+
+  console.error = originalConsoleError;
+
+  // Test case
+  if (!errors.some((e) => e.includes('Error in resolver'))) {
+    errors.forEach(console.error);
+    console.error(
+      '\nError: expected rendering errors ("Error in resolver") to be printed in the console.\n'
+    );
+    process.exit(1);
+  }
+}
+
+runTest();

integration/platform-server/projects/ngmodule/server.ts

@@ -13,6 +13,7 @@ import * as express from 'express';
 import {AppServerModule} from './src/main.server';
 import {join} from 'path';
 import {readFileSync} from 'fs';
+import './prerender';
 
 const app = express();
 const distFolder = join(process.cwd(), 'dist/ngmodule/browser');

integration/platform-server/projects/ngmodule/src/app/app-routing.module.ts

@@ -26,6 +26,15 @@ const routes: Routes = [
         (m) => m.HttpTransferStateOnInitModule
       ),
   },
+  {
+    path: 'error',
+    component: HelloWorldComponent,
+    resolve: {
+      'id': () => {
+        throw new Error('Error in resolver.');
+      },
+    },
+  },
 ];
 
 @NgModule({

integration/platform-server/projects/standalone/prerender.ts

@@ -0,0 +1,43 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+/* tslint:disable:no-console  */
+import 'zone.js/node';
+import {renderApplication} from '@angular/platform-server';
+import bootstrap from './src/main.server';
+import {join} from 'path';
+import {readFileSync} from 'fs';
+
+const distFolder = join(process.cwd(), 'dist/standalone/browser');
+const indexHtml = readFileSync(join(distFolder, 'index.html'), 'utf-8');
+
+async function runTest() {
+  // Test and validate the errors are printed in the console.
+  const originalConsoleError = console.error;
+  const errors: string[] = [];
+  console.error = (error, data) => errors.push(error.toString() + ' ' + data.toString());
+
+  try {
+    await renderApplication(bootstrap, {
+      document: indexHtml,
+      url: '/error',
+    });
+  } catch {}
+
+  console.error = originalConsoleError;
+
+  // Test case
+  if (!errors.some((e) => e.includes('Error in resolver'))) {
+    errors.forEach(console.error);
+    console.error(
+      '\nError: expected rendering errors ("Error in resolver") to be printed in the console.\n'
+    );
+    process.exit(1);
+  }
+}
+
+runTest();

integration/platform-server/projects/standalone/server.ts

@@ -13,6 +13,7 @@ import * as express from 'express';
 import bootstrap from './src/main.server';
 import {join} from 'path';
 import {readFileSync} from 'fs';
+import './prerender';
 
 const app = express();
 const distFolder = join(process.cwd(), 'dist/standalone/browser');

integration/platform-server/projects/standalone/src/app/app.routes.ts

@@ -25,4 +25,13 @@ export const routes: Routes = [
         (c) => c.TransferStateOnInitComponent
       ),
   },
+  {
+    path: 'error',
+    component: HelloWorldComponent,
+    resolve: {
+      'id': () => {
+        throw new Error('Error in resolver.');
+      },
+    },
+  },
 ];

packages/platform-server/src/utils.ts

@@ -90,7 +90,15 @@ async function _render(platformRef: PlatformRef, applicationRef: ApplicationRef)
 
   appendServerContextInfo(applicationRef);
   const output = platformState.renderToString();
-  platformRef.destroy();
+
+  // Destroy the application in a macrotask, this allows pending promises to be settled and errors
+  // to be surfaced to the users.
+  await new Promise<void>((resolve) => {
+    setTimeout(() => {
+      platformRef.destroy();
+      resolve();
+    }, 0);
+  });
 
   return output;
 }

packages/platform-server/test/hydration_spec.ts

@@ -12,7 +12,6 @@ import {CommonModule, DOCUMENT, isPlatformServer, NgComponentOutlet, NgFor, NgIf
 import {MockPlatformLocation} from '@angular/common/testing';
 import {ApplicationRef, Component, ComponentRef, createComponent, destroyPlatform, Directive, ElementRef, EnvironmentInjector, ErrorHandler, getPlatform, inject, Injectable, Input, NgZone, PLATFORM_ID, Provider, TemplateRef, Type, ViewChild, ViewContainerRef, ViewEncapsulation, ɵsetDocument} from '@angular/core';
 import {Console} from '@angular/core/src/console';
-import {InitialRenderPendingTasks} from '@angular/core/src/initial_render_pending_tasks';
 import {getComponentDef} from '@angular/core/src/render3/definition';
 import {NoopNgZone} from '@angular/core/src/zone/ng_zone';
 import {TestBed} from '@angular/core/testing';
@@ -213,7 +212,7 @@ function withDebugConsole() {
   return [{provide: Console, useClass: DebugConsole}];
 }
 
-describe('platform-server integration', () => {
+describe('platform-server hydration integration', () => {
   beforeEach(() => {
     if (typeof ngDevMode === 'object') {
       // Reset all ngDevMode counters.
@@ -279,9 +278,6 @@ describe('platform-server integration', () => {
     async function hydrate(
         html: string, component: Type<unknown>, envProviders?: Provider[],
         hydrationFeatures: HydrationFeature<HydrationFeatureKind>[] = []): Promise<ApplicationRef> {
-      // Destroy existing platform, a new one will be created later by the `bootstrapApplication`.
-      destroyPlatform();
-
       // Get HTML contents of the `<app>`, create a DOM element and append it into the body.
       const container = convertHtmlToDom(html, doc);
       Array.from(container.children).forEach(node => doc.body.appendChild(node));
@@ -4777,7 +4773,7 @@ describe('platform-server integration', () => {
           }
         }
 
-        ssr(SimpleComponent, undefined, withNoopErrorHandler()).catch((err: unknown) => {
+        await ssr(SimpleComponent, undefined, withNoopErrorHandler()).catch((err: unknown) => {
           const message = (err as Error).message;
           expect(message).toContain(
               'During serialization, Angular was unable to find an element in the DOM');

packages/platform-server/test/integration_spec.ts

@@ -532,7 +532,11 @@ if (getDOM().supportsDOMEvents) return;  // NODE only
 
 describe('platform-server integration', () => {
   beforeEach(() => {
-    if (getPlatform()) destroyPlatform();
+    destroyPlatform();
+  });
+
+  afterAll(() => {
+    destroyPlatform();
   });
 
   it('should bootstrap', async () => {
@@ -994,12 +998,11 @@ describe('platform-server integration', () => {
             renderApplication(
                 getStandaloneBoostrapFn(MyServerAppStandalone, RenderHookProviders), options) :
             renderModule(RenderHookModule, options);
-        bootstrap.then(output => {
-          // title should be added by the render hook.
-          expect(output).toBe(
-              '<html><head><title>RenderHook</title></head><body>' +
-              '<app ng-version="0.0.0-PLACEHOLDER" ng-server-context="other">Works!</app></body></html>');
-        });
+        const output = await bootstrap;
+        // title should be added by the render hook.
+        expect(output).toBe(
+            '<html><head><title>RenderHook</title></head><body>' +
+            '<app ng-version="0.0.0-PLACEHOLDER" ng-server-context="other">Works!</app></body></html>');
       });
 
       it('should call multiple render hooks', async () => {