func (e Error) Unwrap() error { return e.cause }

// Error 'error' compatible method.
func (e Error) Error() string {
	if e.msg == "" {
		return "crypto: cause <nil>"
	}
	return e.msg
}

var (
	// ErrInvalidEncryptionMethod indicates that the specified SSE encryption method
	// is not supported.
	ErrInvalidEncryptionMethod = Errorf("The encryption method is not supported")

func Errorf(format string, a ...interface{}) error {
	return Error{err: fmt.Errorf(format, a...)}
}

// Unwrap the internal error.
func (e Error) Unwrap() error { return e.err }

// Error 'error' compatible method.
func (e Error) Error() string {
	if e.err == nil {
		return "replication: cause <nil>"
	}
	return e.err.Error()

func Errorf(format string, a ...interface{}) error {
	return Error{err: fmt.Errorf(format, a...)}
}

// Unwrap the internal error.
func (e Error) Unwrap() error { return e.err }

// Error 'error' compatible method.
func (e Error) Error() string {
	if e.err == nil {
		return "lifecycle: cause <nil>"
	}
	return e.err.Error()

func Errorf(format string, a ...interface{}) error {
	return Error{err: fmt.Errorf(format, a...)}
}

// Unwrap the internal error.
func (e Error) Unwrap() error { return e.err }

// Error 'error' compatible method.
func (e Error) Error() string {
	if e.err == nil {
		return "versioning: cause <nil>"
	}
	return e.err.Error()