public struct CatchAllMiddleware: AsyncMiddleware {
    public func respond(to request: Request, chainingTo next: any AsyncResponder) async throws -> Response {
        do {
            return try await next.respond(to: request)
        } catch is RouteNotFound {
            // No route was found, so this would normally result in a 404. 
            // We can now handle this like any other request.
            // Or we can make treat it like an ErrorMiddleware where we 
            // log purposeful 404s different than `RouteNotFound` 404s.
            ...
        }
    }
}