X_ROUTE_NAVIGATION_INVALID

a route's navigation is not 'prefetch', 'document', 'modal' or { modal: true, prefetch: 'intent' }, or its surface has no client navigation

navigation set to any other value — an object with any other key or value, { modal: true } alone included (that is 'modal') — or set on a page under a surface app.config.ts's navigation.client does not list — no router runs there, so the key would decide nothing. The second half is refused at boot

defineRoute({ ..., navigation: 'prefetch' | 'document' | 'modal' | { modal: true, prefetch: 'intent' } }) on a page whose surface is listed in app.config.ts navigation.client, or remove the key