network: fix logic and logging for sendVersion() errors

It doesn't make sense trying to read from a broken connection and the
disconnect is to be logger from the server on unregistration.

pkg/network/tcp_transport.go

@@ -82,9 +82,8 @@ func (t *TCPTransport) handleConn(conn net.Conn) {
 	t.server.register <- p
 
 	// When a new peer is connected we send out our version immediately.
-	if err := t.server.sendVersion(p); err != nil {
-		t.log.Error("error on sendVersion", zap.Stringer("addr", p.RemoteAddr()), zap.Error(err))
-	}
+	err = t.server.sendVersion(p)
+	if err == nil {
 		r := io.NewBinReaderFromIO(p.conn)
 		for {
 			msg := &Message{}
@@ -100,6 +99,7 @@ func (t *TCPTransport) handleConn(conn net.Conn) {
 				break
 			}
 		}
+	}
 	t.server.unregister <- peerDrop{p, err}
 	p.Disconnect(err)
 }