Discriminated unions for state

A discriminated union removes impossible states:

type State =
  | { status: "idle" }
  | { status: "loading" }
  | { status: "ok"; data: User[] }
  | { status: "error"; message: string };

With three booleans you can represent loading and error simultaneously; with this you cannot, and the compiler enforces handling each case.

The reporting layer, until something forces it. It is the part that feels productive to build and the part nobody opens twice.