Pass ...Wrapper list to New constructor

[Southclaws]

A pattern I've seen pop up in usage of Fault is constructing a new error then immediately wrapping it.

For example, this is from a real codebase, we mostly use sentinel errors for fault.News but it still pops up from time to time.

return nil, fault.Wrap(fault.New("user account not found"),
	fctx.With(ctx),
	ftag.With(ftag.NotFound),
	fmsg.WithDesc("not found",
		"No account could be found with the specified email address."),

Two problems:

• fault.Wrap(fault.New is noisy and verbose
• "user account not found" + "not found" is pointless duplication
  • results in three container{} wraps
  • more writing
  • that issue is covered here: Redesign fmsg to be less verbose and more useful. #32

Ideal interface:

return nil, fault.New("user account not found",
	fctx.With(ctx),
	ftag.With(ftag.NotFound),
	fmsg.With("No account could be found with the specified email address."),

Mainly what I'd like to tackle is giving fault.New a new signature:

func New(message string, w ...Wrapper) error

And immediately perform the wrapping internally if w contains any elements. This would allow you to create new errors and immediately pass them through your wrappers of choice without the need to first create the error then pass it to Wrap().

It would also make the wrapped sentinel pattern a bit less verbose too (a pattern for declaring sentinel errors with pre-determined wrappers such as error tags)

// Before
var (
    ErrEmptyPassword     = fault.Wrap(fault.New("password parameter is empty"), ftag.With(ftag.InvalidArgument))
    ErrUserNotFound      = fault.Wrap(fault.New("user account not found"), ftag.With(ftag.NotFound))
)

// After
var (
    ErrEmptyPassword     = fault.New("password parameter is empty", ftag.With(ftag.InvalidArgument))
    ErrUserNotFound      = fault.New("user account not found", ftag.With(ftag.NotFound))
)