how to handle "not found (404)" page?

[Eserkani]

Hi
I want to add page 404. But I do not know if I did it right or not.
To do this, I add the following line.
{ path: "(.*)", load: () => import(/* webpackChunkName: 'not-found' */ "./not-found"), // action: () => '<h1>Not Found</h1>' },
I also designed not-found.js
The following code is the contents of my router.js:
`import UniversalRouter from 'universal-router';
import routes from './routes';
import { goTo } from './util/generalUtil';

export default new UniversalRouter(routes, {
resolveRoute(context, params) {
console.log("context.route 😍😍😍", context.route)
if (typeof context.route.load === 'function') {
return context.route
.load()
.then(action => action.default(context, params));
}
// else {
// console.log("😢😢😢😢😢")
// goTo("./not-found")
// }
if (typeof context.route.action === 'function') {
return context.route.action(context, params);
}
return undefined;
},
});
`
The following error occurs when testing:

[frenzzy]

It seems your not-found.js is missing export default part. Can you show your not-found.js?