bridge config: Use unreachable, not None.expect

                            "`addrs` contains hostname and port, but only numeric addresses are supported for a direct bridge connection",

                        ))

                    } else {

                        // panic! causes a clippy complaint, so panic like this

                        None.expect("BridgeAddr is neither addr nor named")

                        unreachable!("BridgeAddr is neither addr nor named")

                    }

                }).collect::<Result<Vec<SocketAddr>,&str>>().map_err(|problem| inconsist_transp(

                    "addrs",