From e41e2015bfc37672fb67014ae38f31b63f0bb256 Mon Sep 17 00:00:00 2001
From: Alan Agius <alanagius@google.com>
Date: Sat, 9 Sep 2023 09:37:23 +0000
Subject: [PATCH] fix(@angular-devkit/build-angular): avoid spawning workers
 when there are no routes to prerender

This commit fixes an issue were previously we spawned piscina with `maxThreads` set to `0` which causes it to exit with a non zero error code when there are no routes to prerender.

Now, in the application builder we exit at n earlier stage if there are no routes to prerender.
---
 .../src/utils/server-rendering/prerender.ts      | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/packages/angular_devkit/build_angular/src/utils/server-rendering/prerender.ts b/packages/angular_devkit/build_angular/src/utils/server-rendering/prerender.ts
index d03d4821fd72..dc3eb7ecd4cc 100644
--- a/packages/angular_devkit/build_angular/src/utils/server-rendering/prerender.ts
+++ b/packages/angular_devkit/build_angular/src/utils/server-rendering/prerender.ts
@@ -37,7 +37,19 @@ export async function prerenderPages(
   warnings: string[];
   errors: string[];
 }> {
+  const output: Record<string, string> = {};
+  const warnings: string[] = [];
+  const errors: string[] = [];
   const allRoutes = await getAllRoutes(tsConfigPath, appShellOptions, prerenderOptions);
+
+  if (allRoutes.size < 1) {
+    return {
+      errors,
+      warnings,
+      output,
+    };
+  }
+
   const outputFilesForWorker: Record<string, string> = {};
 
   for (const { text, path } of outputFiles) {
@@ -65,10 +77,6 @@ export async function prerenderPages(
     ],
   });
 
-  const output: Record<string, string> = {};
-  const warnings: string[] = [];
-  const errors: string[] = [];
-
   try {
     const renderingPromises: Promise<void>[] = [];