message: network-ntt: Fix up server::{Error,ErrorKind}
diff: @@ -3,10 +3,11 @@ use std::{error, fmt};
  /// Represents errors that can be returned by the node client implementation.
  #[derive(Debug)]
  pub struct Error {
  - kind: String,
  + kind: ErrorKind,
  source: Box<dyn error::Error + Send + Sync>,
  }
  +#[derive(Copy, Clone, Debug, Eq, PartialEq)]
  pub enum ErrorKind {
  Handshake,
  Connect,
  