404 pages can still be indexed by crawlers

[bneijt]

https://stackoverflow.com/questions/14779190/in-a-single-page-app-what-is-the-right-way-to-deal-with-wrong-urls-404-errors mentiones there should be a <meta name="robots" content="noindex"> for the 404 page.

It is probably better to have a dedicated 404 page entrypoint and an unfound redirect to that entrypoint, like angular suggests:

 {path: '404', component: NotFoundComponent},
 {path: '**', redirectTo: '/404'}

And add the meta tag of 404 to the not found page.