def _error_handler(data, unique_id):
        """Called when data first received

        :param data: Received data
        :param unique_id: Unique id
        :return: True if error present
        """
        if data.get('statusCode') == 'FAILURE':
            logger.error('[Subscription: %s] %s: %s' % (unique_id, data.get('errorCode'), data.get('errorMessage')))
            if data.get('connectionClosed'):
                return True
        if data.get('status'):
            # Clients shouldn't disconnect if status 503 is returned; when the stream
            # recovers updates will be sent containing the latest data
            logger.warning('[Subscription: %s] status: %s' % (unique_id, data['status']))