InferProps is unknown for a defineHandler loader with middleware #489

Same kind of issue as #478. InferProps gives unknown when defineHandler gets middleware:

export const loader = defineHandler(auth, async (c) => {
  const book = await findBook(c.req.param('id'));
  if (!book) return c.notFound();
  return { book };
});

type Props = InferProps<typeof loader>;
// expected: { book: Book }
// actual:   unknown

The middleware overloads return TypedHandler without type arguments, so __output is unknown. The runtime already unwraps the return value as props, so only the type is wrong.

Returning TypedHandler<{}, Exclude<Awaited<R>, Response>> from the middleware overloads too, like the single-handler one, fixes it. Fix and type tests: ashunar0@61f7401

Happy to open a PR if that works for you.