flux pointer exception code example

Example: flux pointer exception

@Repository 
@Override
public Mono<JobClient> getJobById(Long id)  {
    if(jobStores.get(id) == null) throw new ClientNotfoundException();
    return Mono.just(jobStores.get(id)).onErrorResume(e -> Mono.error(new ClientNotfoundException("Correct ID is required"+e)));
}