template<typename SerializableMessage>
void MessageConnection::Send(const SerializableMessage &data, unsigned long contentID)
{
    AssertInMainThreadContext();

    const size_t dataSize = data.Size(); <-- crash

    NetworkMessage *msg = StartNewMessage(data.MessageID(), dataSize); <-- crash shows here in dump, but prolly happens on previous line?

    if (dataSize > 0)
    {
        DataSerializer mb(msg->data, dataSize);
        data.SerializeTo(mb);
        assert(mb.BytesFilled() == dataSize);
    }

    msg->id = data.MessageID();
    msg->contentID = contentID;
    msg->inOrder = data.inOrder;
    msg->priority = data.priority;
    msg->reliable = data.reliable;

    EndAndQueueMessage(msg);
}