fix(@angular/build): serve extensionless assets without transformation

Extensionless files are now served directly without being processed by the underlying transformation pipeline. This ensures that such assets are delivered unmodified and prevents potential serving errors.

Closes #32560

Author: alan-agius4

packages/angular/build/src/builders/dev-server/tests/behavior/build-assets_spec.ts

@@ -21,6 +21,26 @@ describeServeBuilder(executeDevServer, DEV_SERVER_BUILDER_INFO, (harness, setupT
     "import {foo} from 'unresolved'; /* a comment */const foo = `bar`;\n\n\n";
 
   describe('Behavior: "browser builder assets"', () => {
+    it('serves a project extensionless asset unmodified', async () => {
+      await harness.writeFile('src/extensionless', javascriptFileContent);
+
+      setupTarget(harness, {
+        assets: ['src/extensionless'],
+        optimization: {
+          scripts: true,
+        },
+      });
+
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+      });
+
+      const { result, response } = await executeOnceAndFetch(harness, 'extensionless');
+
+      expect(result?.success).toBeTrue();
+      expect(await response?.text()).toContain(javascriptFileContent);
+    });
+
     it('serves a project JavaScript asset unmodified', async () => {
       await harness.writeFile('src/extra.js', javascriptFileContent);
 

packages/angular/build/src/tools/vite/middlewares/assets-middleware.ts

@@ -45,8 +45,8 @@ export function createAngularAssetsMiddleware(
     // Rewrite all build assets to a vite raw fs URL
     const asset = assets.get(pathname);
     if (asset) {
-      // This is a workaround to serve CSS, JS and TS files without Vite transformations.
-      if (JS_TS_REGEXP.test(extension) || CSS_PREPROCESSOR_REGEXP.test(extension)) {
+      // This is a workaround to serve extensionless, CSS, JS and TS files without Vite transformations.
+      if (!extension || !JS_TS_REGEXP.test(extension) || CSS_PREPROCESSOR_REGEXP.test(extension)) {
         const contents = readFileSync(asset.source);
         const etag = `W/${createHash('sha256').update(contents).digest('hex')}`;
         if (checkAndHandleEtag(req, res, etag)) {