pub fn not_found_fallback(
template: Option<String>,
) -> impl Fn(Request<Body>) -> Pin<Box<dyn Future<Output = Response<Body>> + Send>> + Clone + Send + Sync + 'staticExpand description
Build an axum fallback handler that renders the configured 404
template. Used when not_found_template is set but
slash_redirect is Off — App::build skips the slash redirect
path and installs this directly.