webclient onErrorResume does not work

[781574155]

            var result = client.initialize()
                    .onErrorResume(e -> Mono.empty())
                    .block();

when I connect to a 404 endpoint, there is still error print on screen after I setup onErrorResume.

Please finish this:

Not only non-200-ok response, but also 'Connection refused: getsockopt'

[781574155]

when the server is offline, there will be an error log in console. I expect not as I have specify an onErrorResume.