E0113: match isn't exhaustive

A match must cover every value of its subject. The message names a value no case matches.

Wrong

func describe(r Result[int]) string {
	match r {
	case Ok(n):
		return fmt.Sprint(n)
	}
}

Right

func describe(r Result[int]) string {
	match r {
	case Ok(n):
		return fmt.Sprint(n)
	case Err(err):
		return err.Error()
	}
}