Why is AsyncState<T> better than State<T> for managing async state?

type Status = "idle" | "loading" | "success" | "error";

interface State<T> {
  status: Status;
  data: T | null;
  error: string | null;
}

type AsyncState<T> =
  | { status: "idle"; data: null; error: null }
  | { status: "loading"; data: null; error: null }
  | { status: "success"; data: T; error: null }
  | { status: "error"; data: null; error: string };