bugfix

    if (_parent != nullptr) {

        _parent->_child_connections.erase(_original_dcid);

        _parent->_child_connections.erase(_local_cid);

        // Child connections share the parent's socket fd — do NOT close it.

        // Invalidate _Socket so that ~udp() won't call ::close() on the

        // parent's listening socket (which would cause a double-close /

        // "free(): invalid pointer" crash when the parent or another child

        // tries to use the already-closed fd).

        _Socket = -1;

    }

    // Clean up streams