Return None when no IPs could be resolved

src/util.rs

@@ -84,5 +84,8 @@ pub fn parse_and_resolve_peer_addr(peer: &str) -> Option<(NodeID, Vec<SocketAddr
 		.to_socket_addrs()
 		.ok()?
 		.collect::<Vec<_>>();
+	if hosts.is_empty() {
+		return None;
+	}
 	Some((pubkey, hosts))
 }