### 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)

MAKE_ROOM(1 + 1 + 4 + 4 + 4 + 4 * sync_ids.size() + 4 + nlen + (is_custom ? 4 + spawn_arg_size : 0) + state_size);
	uint8_t *ptr = packet_cache.ptrw();
	ptr[0] = (uint8_t)SceneMultiplayer::NETWORK_COMMAND_SPAWN;
	ptr[1] = scene_id;
	int ofs = 2;
	ofs += encode_uint32(path_id, &ptr[ofs]);
	ofs += encode_uint32(nid, &ptr[ofs]);
	ofs += encode_uint32(sync_ids.size(), &ptr[ofs]);
	ofs += encode_uint32(nlen, &ptr[ofs]);
	for (uint32_t snid : sync_ids) {
		ofs += encode_uint32(snid, &ptr[ofs]);
	}
	ofs += encode_cstring(cname.get_data(), &ptr[ofs]);
	
	if (is_custom) {
		ofs += encode_uint32(spawn_arg_size, &ptr[ofs]);
		Error err = MultiplayerAPI::encode_and_compress_variant(spawn_arg, &ptr[ofs], spawn_arg_size, false);
		ERR_FAIL_COND_V(err, err);
		ofs += spawn_arg_size;
	}
	
	if (state_size) {
		Error err = MultiplayerAPI::encode_and_compress_variants(state_varp.ptrw(), state_varp.size(), &ptr[ofs], state_size);
		ERR_FAIL_COND_V(err, err);
		ofs += state_size;
	}
	r_len = ofs;
	return OK;
}
Error SceneReplicationInterface::_make_despawn_packet(Node *p_node, int &r_len) {