Must not wrap io.EOF

[andig]

From the Go docs:

// EOF is the error returned by Read when no more input is available.
// (Read must return EOF itself, not an error wrapping EOF,
// because callers will test for EOF using ==.)
// Functions should return EOF only to signal a graceful end of input.
// If the EOF occurs unexpectedly in a structured data stream,
// the appropriate error is either [ErrUnexpectedEOF] or some other error
// giving more detail.
var EOF = errors.New("EOF")

however, Conn.reader (and probably others) wrap io.EOF:

func (c *Conn) reader(ctx context.Context) (_ MessageType, _ io.Reader, err error) {
	defer errd.Wrap(&err, "failed to get reader")


// Wrap wraps err with fmt.Errorf if err is non nil.
// Intended for use with defer and a named error return.
// Inspired by https://github.com/golang/go/issues/32676.
func Wrap(err *error, f string, v ...any) {
	if *err != nil {
		*err = fmt.Errorf(f+": %w", append(v, *err)...)
	}
}

This leads to errors such as hashicorp/yamux#167.

I'd propose special-casing Wrap to check for io.EOF and would be happy to open a PR.