fix(@angular-devkit/build-angular): avoid double sourcemap comments with esbuild dev-server

When using the esbuild-based browser application builder with the dev-server builder, sourcemap
URL comments were unintentionally doubled due to vite adding an additional inline sourcemap comment
when processing the JavaScript files for the application. To avoid this, JavaScript files now have
any sourcemap URL comments removed prior to being processed by vite. The sourcemap content is already
passed directly to vite and allows the sourcemaps to be processed and provided to the browser as needed
without the previously existing sourcemap URL comment. The removal is done without modifying the esbuild-
based builder's options to avoid assuming the builder used with the dev-server has sourcemap options that
allow hidden sourcemap generation.

Author: clydin

packages/angular_devkit/build_angular/src/builders/dev-server/vite-server.ts

@@ -214,15 +214,20 @@ async function setupServer(
         },
         load(id) {
           const [file] = id.split('?', 1);
-          const code = outputFiles.get(file)?.contents;
-          const map = outputFiles.get(file + '.map')?.contents;
+          const codeContents = outputFiles.get(file)?.contents;
+          if (codeContents === undefined) {
+            return;
+          }
 
-          return (
-            code && {
-              code: code && Buffer.from(code).toString('utf-8'),
-              map: map && Buffer.from(map).toString('utf-8'),
-            }
-          );
+          const code = Buffer.from(codeContents).toString('utf-8');
+          const mapContents = outputFiles.get(file + '.map')?.contents;
+
+          return {
+            // Remove source map URL comments from the code if a sourcemap is present.
+            // Vite will inline and add an additional sourcemap URL for the sourcemap.
+            code: mapContents ? code.replace(/^\/\/# sourceMappingURL=[^\r\n]*/gm, '') : code,
+            map: mapContents && Buffer.from(mapContents).toString('utf-8'),
+          };
         },
         configureServer(server) {
           // Assets and resources get handled first