typedef void (*SilcPacketErrorCb)(SilcPacketEngine engine,
                                      SilcPacketStream stream,
                                      SilcPacketError error,
                                      void *callback_context,
                                      void *stream_context);

    The error callback that is called by the packet engine if an error
    occurs.  The `error' will indicate the error.  This callback is set
    in the SilcPacketCallbacks structure.