react ssr true 404

1const context = {};
2const markup = ReactDOMServer.renderToString(
3  <StaticRouter location={req.url} context={context}>
4    <App />
5  </StaticRouter>
6);
7
8if (context.url) {
9  // Somewhere a `<Redirect>` was rendered
10  redirect(301, context.url);
11} else {
12  // we're good, send the response
13}
14