fix: generics union

[tfs-tada]

type Human<T> = { body: T; isHuman: true };
type Robot<T> = { body: T; isHuman: false; uuid: string };
type User<T> = Human<T> | Robot<T>;
const jiro = { body: { name: "jiro" }, isHuman: true, uuid: "123" } as const;
const user: User<{ name: string }> = jiro;