fix(@angular/build): fail build and exclude routes when prerendering fails

packages/angular/build/src/builders/application/execute-post-bundle.ts

@@ -157,7 +157,13 @@ export async function executePostBundleSteps(
       'The "index" option is required when using the "ssg" or "appShell" options.',
     );
 
-    const { output, warnings, errors, serializableRouteTreeNode } = await prerenderPages(
+    const {
+      output,
+      warnings,
+      errors,
+      serializableRouteTreeNode,
+      prerenderedRoutes: generatedPrerenderedRoutes,
+    } = await prerenderPages(
       workspaceRoot,
       baseHref,
       appShellOptions,
@@ -171,6 +177,7 @@ export async function executePostBundleSteps(
 
     allErrors.push(...errors);
     allWarnings.push(...warnings);
+    Object.assign(prerenderedRoutes, generatedPrerenderedRoutes);
 
     const indexHasBeenPrerendered = output[indexHtmlOptions.output];
     for (const [path, { content, appShellRoute }] of Object.entries(output)) {
@@ -195,10 +202,6 @@ export async function executePostBundleSteps(
     const serializableRouteTreeNodeForManifest: WritableSerializableRouteTreeNode = [];
     for (const metadata of serializableRouteTreeNode) {
       serializableRouteTreeNodeForManifest.push(metadata);
-
-      if (metadata.renderMode === RouteRenderMode.Prerender && !metadata.route.includes('*')) {
-        prerenderedRoutes[metadata.route] = { headers: metadata.headers };
-      }
     }
 
     if (outputMode === OutputMode.Server) {

packages/angular/build/src/utils/server-rendering/prerender.ts

@@ -10,7 +10,10 @@ import { readFile } from 'node:fs/promises';
 import { extname, posix } from 'node:path';
 import { NormalizedApplicationBuildOptions } from '../../builders/application/options';
 import { OutputMode } from '../../builders/application/schema';
-import { BuildOutputAsset } from '../../tools/esbuild/bundler-execution-result';
+import {
+  BuildOutputAsset,
+  PrerenderedRoutesRecord,
+} from '../../tools/esbuild/bundler-execution-result';
 import { BuildOutputFile, BuildOutputFileType } from '../../tools/esbuild/bundler-files';
 import { assertIsError } from '../error';
 import { toPosixPath } from '../path';
@@ -65,6 +68,7 @@ export async function prerenderPages(
   output: PrerenderOutput;
   warnings: string[];
   errors: string[];
+  prerenderedRoutes: PrerenderedRoutesRecord;
   serializableRouteTreeNode: SerializableRouteTreeNode;
 }> {
   const rawOutputFiles: Record<string, string> = {};
@@ -167,6 +171,7 @@ export async function prerenderPages(
       errors,
       warnings,
       output: {},
+      prerenderedRoutes: {},
       serializableRouteTreeNode,
     };
   }
@@ -200,10 +205,22 @@ export async function prerenderPages(
 
   errors.push(...renderingErrors);
 
+  const prerenderedRoutes: PrerenderedRoutesRecord = {};
+  const baseHrefPathnameWithLeadingSlash = new URL(baseHref, 'http://localhost').pathname;
+
+  for (const metadata of serializableRouteTreeNodeForPrerender) {
+    const outPath = getRouteOutPath(metadata.route, baseHrefPathnameWithLeadingSlash);
+
+    if (output[outPath]) {
+      prerenderedRoutes[metadata.route] = { headers: metadata.headers };
+    }
+  }
+
   return {
     errors,
     warnings,
     output,
+    prerenderedRoutes,
     serializableRouteTreeNode,
   };
 }
@@ -227,22 +244,15 @@ async function renderPages(
 
   const baseHrefPathnameWithLeadingSlash = new URL(baseHref, 'http://localhost').pathname;
   const appShellRouteWithoutBaseHref = appShellRoute
-    ? addTrailingSlash(appShellRoute).startsWith(baseHrefPathnameWithLeadingSlash)
-      ? addLeadingSlash(appShellRoute.slice(baseHrefPathnameWithLeadingSlash.length))
-      : addLeadingSlash(appShellRoute)
+    ? addLeadingSlash(getRouteWithoutBaseHref(appShellRoute, baseHrefPathnameWithLeadingSlash))
     : undefined;
 
   const routesToRender: { route: string; outPath: string; isAppShell: boolean }[] = [];
 
   for (const { route, redirectTo } of serializableRouteTreeNode) {
     // Remove the base href from the file output path.
-    const routeWithoutBaseHref = addTrailingSlash(route).startsWith(
-      baseHrefPathnameWithLeadingSlash,
-    )
-      ? addLeadingSlash(route.slice(baseHrefPathnameWithLeadingSlash.length))
-      : route;
-
-    const outPath = stripLeadingSlash(posix.join(routeWithoutBaseHref, 'index.html'));
+    const routeWithoutBaseHref = getRouteWithoutBaseHref(route, baseHrefPathnameWithLeadingSlash);
+    const outPath = getRouteOutPath(route, baseHrefPathnameWithLeadingSlash);
 
     if (typeof redirectTo === 'string') {
       output[outPath] = { content: generateRedirectStaticPage(redirectTo), appShellRoute: false };
@@ -305,20 +315,20 @@ async function renderPages(
       const renderBatchPromise: Promise<RenderResult> = renderWorker.run(urls);
       const batchResultPromise = renderBatchPromise
         .then((results) => {
-          for (const { url, content, error } of results) {
-            if (error) {
-              errors.push(`An error occurred while prerendering route '${url}'.\n\n${error}`);
+          for (const result of results) {
+            if ('error' in result) {
+              errors.push(
+                `An error occurred while prerendering route '${result.url}'.\n\n${result.error}`,
+              );
               continue;
             }
 
-            if (content !== null) {
-              const routeInfo = routeOutPathMap.get(url);
-              if (routeInfo) {
-                output[routeInfo.outPath] = {
-                  content,
-                  appShellRoute: routeInfo.isAppShell,
-                };
-              }
+            const routeInfo = routeOutPathMap.get(result.url);
+            if (routeInfo) {
+              output[routeInfo.outPath] = {
+                content: result.content,
+                appShellRoute: routeInfo.isAppShell,
+              };
             }
           }
         })
@@ -439,3 +449,15 @@ async function getAllRoutes(
     void renderWorker.destroy();
   }
 }
+
+function getRouteWithoutBaseHref(route: string, baseHrefPathname: string): string {
+  return addTrailingSlash(route).startsWith(baseHrefPathname)
+    ? addLeadingSlash(route.slice(baseHrefPathname.length))
+    : route;
+}
+
+function getRouteOutPath(route: string, baseHrefPathname: string): string {
+  const routeWithoutBaseHref = getRouteWithoutBaseHref(route, baseHrefPathname);
+
+  return stripLeadingSlash(posix.join(routeWithoutBaseHref, 'index.html'));
+}

packages/angular/build/src/utils/server-rendering/render-worker.ts

@@ -21,11 +21,15 @@ export interface RenderWorkerData extends ESMInMemoryFileLoaderWorkerData {
   hasSsrEntry: boolean;
 }
 
-export interface RenderResultItem {
-  url: string;
-  content: string | null;
-  error?: string;
-}
+export type RenderResultItem =
+  | {
+      url: string;
+      content: string;
+    }
+  | {
+      url: string;
+      error: string;
+    };
 
 export type RenderResult = RenderResultItem[];
 
@@ -74,12 +78,16 @@ async function renderPages(urls: string[]): Promise<RenderResult> {
   for (const currentUrl of urls) {
     try {
       const content = await renderPage(currentUrl, angularServerApp);
+
+      if (content === null) {
+        throw new Error('The content returned was empty.');
+      }
+
       results.push({ url: currentUrl, content });
     } catch (err) {
       assertIsError(err);
       results.push({
         url: currentUrl,
-        content: null,
         error: err.stack ?? err.message ?? err.code ?? `${err}`,
       });
     }

tests/e2e/tests/build/prerender/error-component-render.ts

@@ -0,0 +1,72 @@
+import { existsSync } from 'node:fs';
+import assert, { match } from 'node:assert';
+import { getGlobalVariable } from '../../../utils/env';
+import { expectFileNotToExist, readFile, rimraf, writeMultipleFiles } from '../../../utils/fs';
+import { installWorkspacePackages } from '../../../utils/packages';
+import { ng } from '../../../utils/process';
+import { useSha } from '../../../utils/project';
+import { expectToFail } from '../../../utils/utils';
+
+export default async function () {
+  const useWebpackBuilder = !getGlobalVariable('argv')['esbuild'];
+  if (useWebpackBuilder) {
+    return;
+  }
+
+  // Forcibly remove in case another test doesn't clean itself up.
+  await rimraf('node_modules/@angular/ssr');
+  await ng('add', '@angular/ssr', '--skip-confirmation');
+  await useSha();
+  await installWorkspacePackages();
+
+  await writeMultipleFiles({
+    'src/app/app.routes.ts': `
+      import { Routes } from '@angular/router';
+      import { Component } from '@angular/core';
+
+      @Component({
+        selector: 'app-home',
+        standalone: true,
+        template: '<p>home works!</p>',
+      })
+      export class HomeRoute {}
+
+      @Component({
+        selector: 'app-second',
+        standalone: true,
+        template: '<p>second works!</p>',
+      })
+      export class SecondRoute {
+        constructor() {
+          throw new Error('render failure');
+        }
+      }
+
+      export const routes: Routes = [
+        { path: '', component: HomeRoute },
+        { path: 'second', component: SecondRoute },
+      ];
+    `,
+    'src/app/app.routes.server.ts': `
+      import { RenderMode, ServerRoute } from '@angular/ssr';
+
+      export const serverRoutes: ServerRoute[] = [
+        { path: 'second', renderMode: RenderMode.Prerender },
+        { path: '**', renderMode: RenderMode.Prerender },
+      ];
+    `,
+  });
+
+  const { message } = await expectToFail(() => ng('build', '--output-mode=server'));
+
+  match(message, /An error occurred while prerendering route '\/second'\./);
+
+  await expectFileNotToExist('dist/test-project/browser/second/index.html');
+
+  // prerendered-routes.json should only contain successfully prerendered routes if emitted
+  const statsPath = 'dist/test-project/prerendered-routes.json';
+  if (existsSync(statsPath)) {
+    const stats = JSON.parse(await readFile(statsPath));
+    assert.strictEqual(stats.routes['/second'], undefined);
+  }
+}