return the command output on error as well

go/linguaevalia.go

	// `go run` it
	res, err := runCode(f)
	if err != nil {
		return nil, err
		return res, err
	}
	// remove the file
	os.Remove(f.Name())
	//fmt.Println(string(code))
	res, err := Go.Eval(string(code))
	if err != nil {
		http.Error(w, err.Error(), http.StatusNotAcceptable)
		http.Error(w, string(res), http.StatusNotAcceptable)
		return
	}
	w.Write(res)