Fix build breaks

net/vmesshandler.go

@@ -8,7 +8,7 @@ type VMessHandler struct {
 }
 
 func (*VMessHandler) Listen(port uint8) error {
-	listener, err := net.Listen("tcp", ":"+string(port))
+	_, err := net.Listen("tcp", ":"+string(port))
 	if err != nil {
 		return err
 	}