Failure handler issue using Vertx web routes and Minity in a Quarkus application - vert.x

Question

I have tried to use Munity API and Vertx Route together. The complete codes are here.
I defined a router rule like this.
router.put("/posts/:id").consumes("application/json").handler(BodyHandler.create()).handler(handlers::update);
And the handler implementation is like this.
LOGGER.log(Level.INFO, "\npath param id: {0}\nrequest body: {1}", new Object[]{id, body});
var form = fromJson(body, PostForm.class);
this.posts.findById(UUID.fromString(id))
.onFailure(PostNotFoundException.class).invoke(ex -> rc.response().setStatusCode(404).end())
.map(
post -> {
post.setTitle(form.getTitle());
post.setContent(form.getContent());
return this.posts.update(UUID.fromString(id), post);
}
)
.subscribe()
.with(data -> rc.response().setStatusCode(204).end());
In the findById method , it throws an PostNotFoundException.
public Uni<Post> findById(UUID id) {
return this.client
.preparedQuery("SELECT * FROM posts WHERE id=$1")
.execute(Tuple.of(id))
.map(RowSet::iterator)
// .map(it -> it.hasNext() ? rowToPost(it.next()) : null);
.flatMap(it -> it.hasNext() ? Uni.createFrom().item(rowToPost(it.next())) : Uni.createFrom().failure(PostNotFoundException::new));
}
When running the application, and do update(via HTTP PUT method) on the /posts/postid with a none existing post id, it will print a 404 error status as expected, but there is some pause time in the period.
In another handler method, it calls findById like the following and it works well and responds quickly when it is not found.
this.posts.findById(UUID.fromString(id))
.subscribe()
.with(
post -> rc.response().end(toJson(post)),
throwable -> rc.fail(404, throwable)
);