Go Reflection 取得目前欄位名稱，但在類型不符的非類型字串上出現錯誤

type Issue struct {
  SysId  uuid.UUID  `json:"sysid" maelstrom:"required"`
}

func (i *Issue) Unmarshal(data []byte) error {
  err := json.Unmarshal(data, i)
  if err != nil {
    slog.Error(err.Error())
    return err
  }
  fields := reflect.ValueOf(i).Elem()
  for i := 0; i < fields.NumField(); i++ {
    maelstromTags := fields.Type().Field(i).Tag.Get("maelstrom")
    if strings.Contains(maelstromTags, "required") && fields.Field(i).IsZero() {
      return errors.New("Required field is missing." + fields.Field(i))
    }
  }
  return nil
}

return errors.New("Required field is missing." + fields.Field(i))

<code>
invalid operation: "Required field is missing." + fields.Field(i) (mismatched types untyped string and reflect.Value)
</code>

return errors.New("Required field is missing." + fields.Field(i).String)

<code>
invalid operation: "Required field is missing." + fields.Field(i).String (mismatched types untyped string and func() string)
</code>

return errors.New("Required field is missing." + string(fields.Field(i)))

<code>
cannot convert fields.Field(i) (value of type reflect.Value) to type string [InvalidConversion]
</code>

return fmt.Errorf("required field is missing: %s", fields.Type().Field(i).Name)