src/vs/server/node/webClientServer.ts/WebClientServer/_handleStatic
class WebClientServer:	private async _handleStatic(req: http.IncomingMessage, res: http.ServerResponse, parsedUrl: url.UrlWithParsedQuery): Promise<void> {
		const headers: Record<string, string> = Object.create(null);

		// Strip the this._staticRoute from the path
		const normalizedPathname = decodeURIComponent(parsedUrl.pathname!); // support paths that are uri-encoded (e.g. spaces => %20)
		const relativeFilePath = normalizedPathname.substring(this._staticRoute.length + 1);

		const filePath = join(APP_ROOT, relativeFilePath); // join also normalizes the path
		if (!isEqualOrParent(filePath, APP_ROOT, !isLinux)) {
			return serveError(req, res, 400, `Bad request.`);
		}

		return serveFile(filePath, this._environmentService.isBuilt ? CacheControl.NO_EXPIRY : CacheControl.ETAG, this._logService, req, res, headers);
	}