fix: entrypoint validation without js tag

src/package.ts

@@ -922,13 +922,20 @@ class LaunchEntryPointProcessor extends BaseProcessor {
 	constructor(manifest: Manifest) {
 		super(manifest);
 		if (manifest.main) {
-			this.entryPoints.add(util.normalize(path.join('extension', manifest.main)));
+			this.entryPoints.add(util.normalize(path.join('extension', this.appendJSExt(manifest.main))));
 		}
 		if (manifest.browser) {
-			this.entryPoints.add(util.normalize(path.join('extension', manifest.browser)));
+			this.entryPoints.add(util.normalize(path.join('extension', this.appendJSExt(manifest.browser))));
 		}
 	}
 
+	appendJSExt(filePath: string): string {
+		if (filePath.endsWith('.js')) {
+			return filePath;
+		}
+		return filePath + '.js';
+	}
+
 	onFile(file: IFile): Promise<IFile> {
 		this.entryPoints.delete(util.normalize(file.path));
 		return Promise.resolve(file);
@@ -937,7 +944,9 @@ class LaunchEntryPointProcessor extends BaseProcessor {
 	async onEnd(): Promise<void> {
 		if (this.entryPoints.size > 0) {
 			const files: string = [...this.entryPoints].join(',\n  ');
-			throw new Error(`Extension entrypoint(s) missing. Make sure these files exist and aren't ignored by '.vscodeignore':\n  ${files}`);
+			throw new Error(
+				`Extension entrypoint(s) missing. Make sure these files exist and aren't ignored by '.vscodeignore':\n  ${files}`
+			);
 		}
 	}
 }

src/test/package.test.ts

@@ -1794,7 +1794,7 @@ describe('toContentTypes', () => {
 	});
 });
 
-describe('LaunchEntryPointProcessor', () => {
+describe.only('LaunchEntryPointProcessor', () => {
 	it('should detect when declared entrypoint is not in package', async () => {
 		const manifest = createManifest({
 			main: 'main.js',
@@ -1810,6 +1810,23 @@ describe('LaunchEntryPointProcessor', () => {
 		assert.ok(didErr);
 	});
 
+	it('should work even if .js extension is not mentioned', async () => {
+		const manifest = createManifest({
+			main: './out/src/extension',
+		});
+		const files = [{ path: 'extension/out/src/extension.js', contents: Buffer.from('') }];
+
+		let didErr = false;
+
+		try {
+			await _toVsixManifest(manifest, files);
+			didErr = true;
+		} catch (err: any) {
+			didErr = false;
+		}
+		assert.ok(didErr);
+	});
+
 	it('should accept manifest if no entrypoints defined', async () => {
 		const manifest = createManifest({});
 		const files = [{ path: 'extension/something.js', contents: Buffer.from('') }];