errors.go
func GetSystemErrorCode(err error) SystemErrCode {
	if err == nil {
		return ErrCodeInvalid
	}

	if se, ok := err.(SystemError); ok {
		return se.Code()
	}

	return ErrCodeUnexpected
}
func GetSystemErrorCode(err error) SystemErrCode {
	if err == nil {
		return ErrCodeInvalid
	}

	if se, ok := err.(SystemError); ok {
		return se.Code()
	}

	return ErrCodeUnexpected
}
// GetSystemErrorCode returns the code to report for the given error.  If the error is a
// SystemError, we can get the code directly.  Otherwise treat it as an unexpected error