refactor(@angular/build): adjust code to propagate errors from Piscina

Ensure that errors occurring during initialization are properly propagated,
as Piscina currently swallows errors during worker initialization.
For more details, see:
https://github.com/piscinajs/piscina/blob/b64747233446ca4271e6aed744a740f637e278a5/src/worker.ts#L57

(cherry picked from commit a6eaf2f)

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

@@ -26,10 +26,12 @@ const { outputMode, hasSsrEntry } = workerData as {
   hasSsrEntry: boolean;
 };
 
-let serverURL = DEFAULT_URL;
-
 /** Renders an application based on a provided options. */
 async function extractRoutes(): Promise<RoutersExtractorWorkerResult> {
+  const serverURL = outputMode !== undefined && hasSsrEntry ? await launchServer() : DEFAULT_URL;
+
+  patchFetchToLoadInMemoryAssets(serverURL);
+
   const { ɵextractRoutesAndCreateRouteTree: extractRoutesAndCreateRouteTree } =
     await loadEsmModuleFromMemory('./main.server.mjs');
 
@@ -47,14 +49,4 @@ async function extractRoutes(): Promise<RoutersExtractorWorkerResult> {
   };
 }
 
-async function initialize() {
-  if (outputMode !== undefined && hasSsrEntry) {
-    serverURL = await launchServer();
-  }
-
-  patchFetchToLoadInMemoryAssets(serverURL);
-
-  return extractRoutes;
-}
-
-export default initialize();
+export default extractRoutes;