You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: handler.go
    path of file: ./repos/docker-ce/components/engine/vendor/github.com/docker/distribution/registry/api/errcode
    
    the code of the file until where you have to start completion: package errcode

import (
	"encoding/json"
	"net/http"
)

// ServeJSON attempts to serve the errcode in a JSON envelope. It marshals err
// and sets the content-type header to 'application/json'. It will handle
// ErrorCoder and Errors, and if necessary will create an envelope.
func ServeJSON(w http.ResponseWriter, err error) error {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	var sc int

	switch errs := err.(type) {
	case Errors:
		if len(errs) < 1 {
			break
		}

		if err, ok := errs[0].(ErrorCoder); ok {
			sc = err.ErrorCode().Descrip
    
func ServeJSON(w http.ResponseWriter, err error) error {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	var sc int

	switch errs := err.(type) {
	case Errors:
		if len(errs) < 1 {
			break
		}

		if err, ok := errs[0].(ErrorCoder); ok {
			sc = err.ErrorCode().Descriptor().HTTPStatusCode
		}
	case ErrorCoder:
		sc = errs.ErrorCode().Descriptor().HTTPStatusCode
		err = Errors{err} // create an envelope.
	default:
		// We just have an unhandled error type, so just place in an envelope
		// and move along.
		err = Errors{err}
	}

	if sc == 0 {
		sc = http.StatusInternalServerError
	}

	w.WriteHeader(sc)

	return json.NewEncoder(w).Encode(err)
}