fix(@angular-devkit/build-angular): return 404 for assets that are not found

This commit updates the vite dev-server to return 404 for assets and files that are not found.

Closes angular#26917

Author: alan-agius4

packages/angular_devkit/build_angular/src/tools/vite/angular-memory-plugin.ts

@@ -123,11 +123,6 @@ export function createAngularMemoryPlugin(options: AngularMemoryPluginOptions):
         // The base of the URL is unused but required to parse the URL.
         const pathname = pathnameWithoutBasePath(req.url, server.config.base);
         const extension = extname(pathname);
-        if (!extension) {
-          next();
-
-          return;
-        }
 
         // Rewrite all build assets to a vite raw fs URL
         const assetSourcePath = assets.get(pathname);
@@ -323,24 +318,16 @@ function angularHtmlFallbackMiddleware(
   // Similar to how it is handled in vite
   // https://github.com/vitejs/vite/blob/main/packages/vite/src/node/server/middlewares/htmlFallback.ts#L15C19-L15C45
   if (
-    // Only accept GET or HEAD
-    (req.method !== 'GET' && req.method !== 'HEAD') ||
-    // Has file extensions
-    (req.url && lookupMimeTypeFromRequest(req.url)) ||
-    // Require Accept: text/html or */*
-    !(
-      req.headers.accept === undefined || // equivalent to `Accept: */*`
-      req.headers.accept === '' || // equivalent to `Accept: */*`
+    (req.method === 'GET' || req.method === 'HEAD') &&
+    (!req.url || !lookupMimeTypeFromRequest(req.url)) &&
+    (!req.headers.accept ||
       req.headers.accept.includes('text/html') ||
-      req.headers.accept.includes('*/*')
-    )
+      req.headers.accept.includes('text/*') ||
+      req.headers.accept.includes('*/*'))
   ) {
-    next();
-
-    return;
+    req.url = '/index.html';
   }
 
-  req.url = '/index.html';
   next();
 }