### 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)

for (const Variant &v : delta) {
			vptr[i] = &v;
		}
		int size;
		Error err = MultiplayerAPI::encode_and_compress_variants(vptr, varp.size(), nullptr, size);
		ERR_CONTINUE_MSG(err != OK, "Unable to encode delta state.");
		ERR_CONTINUE_MSG(size > delta_mtu, vformat("Synchronizer delta bigger than MTU will not be sent (%d > %d): %s", size, delta_mtu, sync->get_path()));
		if (ofs + 4 + 8 + 4 + size > delta_mtu) {
			
			_send_raw(packet_cache.ptr(), ofs, p_peer, true);
			ofs = 1;
		}
		if (size) {
			ofs += encode_uint32(sync->get_net_id(), &ptr[ofs]);
			ofs += encode_uint64(indexes, &ptr[ofs]);
			ofs += encode_uint32(size, &ptr[ofs]);
			MultiplayerAPI::encode_and_compress_variants(vptr, varp.size(), &ptr[ofs], size);
			ofs += size;
		}
#ifdef DEBUG_ENABLED
		_profile_node_data("delta_out", oid, size);
#endif
		peers_info[p_peer].last_watch_usecs[oid] = p_usec;
	}
	if (ofs > 1) {
		
		_send_raw(packet_cache.ptr(), ofs, p_peer, true);
	}
}
Error SceneReplicationInterface::on_delta_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) {