### Godot version

4.1.dev4

### System information

Windows 10 - Godot 4.1.dev4 - Compatibility

### Issue description

When you syncronize 2 variables and both are in watched mode (taking out the "sync" property too) the server crashes

### Steps to reproduce

Create a MultiplayerSynchronizer, export 2 variables from a script, connect the server and the client and the server will crash instantly

In the project I give, the server and client are connected automatically when you use 2 debug instances when pressing play

### Minimal reproduction project

[minimalproject.zip](https://github.com/godotengine/godot/files/11665652/minimalproject.zip)

ERR_FAIL_COND_V_MSG(p_buffer_len < 5, ERR_INVALID_DATA, "Invalid spawn packet received");
	int ofs = 1; 
	uint32_t net_id = decode_uint32(&p_buffer[ofs]);
	ofs += 4;
	
	ERR_FAIL_COND_V(!peers_info.has(p_from), ERR_UNAUTHORIZED);
	PeerInfo &pinfo = peers_info[p_from];
	ERR_FAIL_COND_V(!pinfo.recv_nodes.has(net_id), ERR_UNAUTHORIZED);
	Node *node = get_id_as<Node>(pinfo.recv_nodes[net_id]);
	ERR_FAIL_COND_V(!node, ERR_BUG);
	pinfo.recv_nodes.erase(net_id);
	const ObjectID oid = node->get_instance_id();
	ERR_FAIL_COND_V(!tracked_nodes.has(oid), ERR_BUG);
	MultiplayerSpawner *spawner = get_id_as<MultiplayerSpawner>(tracked_nodes[oid].spawner);
	ERR_FAIL_COND_V(!spawner, ERR_DOES_NOT_EXIST);
	ERR_FAIL_COND_V(p_from != spawner->get_multiplayer_authority(), ERR_UNAUTHORIZED);
	if (node->get_parent() != nullptr) {
		node->get_parent()->remove_child(node);
	}
	node->queue_free();
	spawner->emit_signal(SNAME("despawned"), node);
	return OK;
}
bool SceneReplicationInterface::_verify_synchronizer(int p_peer, MultiplayerSynchronizer *p_sync, uint32_t &r_net_id) {