react ssr true 404

const context = {};
const markup = ReactDOMServer.renderToString(
  <StaticRouter location={req.url} context={context}>
    <App />
  </StaticRouter>
);

if (context.url) {
  // Somewhere a `<Redirect>` was rendered
  redirect(301, context.url);
} else {
  // we're good, send the response
}