fix: union func

[tfs-tada]

• 原因特定からやること

type Props = { target: string };
type Action = Props | ((prevState: Props) => Props);
type Dispatch = (action: Action) => void;
const func: Dispatch = (prevState) => ({ target: "new" });
const newState = { hoge: "hoge" };
func({ target: "old", ...newState }); // エラーが出ない