rust hyperlocal attempt at low level server unix socket listener.. fail not working

gistfile1.txt

extern crate hyper;
extern crate hyperlocal;

use std::os::unix::net::UnixListener;
use hyper::{Response, rt::{Future, Stream}, service::service_fn};
use hyperlocal::server::{Http, Incoming};

fn main () {
    if let Err(err) =  std::fs::remove_file("hyperlocal_test_echo_server_2.sock") {
        if err.kind() != std::io::ErrorKind::NotFound {
            panic!("{}", err);
        }
    }
    let listener = UnixListener::bind("hyperlocal_test_echo_server_2.sock").unwrap();
    let incoming = Incoming::from_std(listener, &Default::default()).unwrap();
    let serve = Http::new().serve_incoming(
        incoming,
        move || service_fn(
            |req| Ok::<_, hyper::Error>(Response::new(req.into_body()))
        )
    );

    let server = serve.for_each(|connecting| {
        connecting
            .then(|connection| {
                let connection = connection.unwrap();
                Ok::<_, hyper::Error>(connection)
            })
            .flatten()
            .map_err(|err| {
                std::io::Error::new(
                    std::io::ErrorKind::Other,
                    format!("failed to serve connection: {}", err),
                )
            })
    });
}