Static Pre-rendering types inconsistency

[bespoyasov]

Hey!

I think I found an error in Static Prerendering docs.

There is an example of using an async function as a pre-render request function in docs:

module.exports = new Router().prerender(async () => {
  const paths = await fetchCategoryPathsFromAPI()
  return paths.map(path => ({ path }))
})

However, TS won't let me compile this code since:

The same goes for the Next.js example:

The only workaround I found is to make any request function async and use an array of them as an argument for prerender():

Is this intentional?
If so, I can create a PR to update docs for this page.