errors.go
func (list ErrorList) Error() string {
	if len(list) == 0 {
		return "Empty ErrorList"
	}
	var b strings.Builder
	for _, err := range list {
		fmt.Fprintln(&b, err)
	}
	return b.String()
}
func (list ErrorList) Error() string {
	if len(list) == 0 {
		return "Empty ErrorList"
	}
	var b strings.Builder
	for _, err := range list {
		fmt.Fprintln(&b, err)
	}
	return b.String()
}
// Error calls fmt.Println for of every error in the list
// and returns the concernated text.
// Can be called for a nil ErrorList.