Why is the NextApiResponse type generic, but `NextApiRequest` is not?

typed-api-request.d.ts

// Add type safety to NextApiRequest
type TypedNextApiRequest<Q, B> = Omit<NextApiRequest, 'body' | 'query'> & {
  // make req.query have the keys we expect, but AsQuery will turn the values
  // into strings or string arrays. Partial is there because you never know
  // whether the request will be well-formed
  query: Partial<AsQuery<Q>>;
  // make req.body have the keys and value types we expect, however, know that
  // the data will be deserialized from JSON, so, for example, Dates will be
  // strings. again Partial is there to enforce defensive code
  body: Partial<Deserialized<B>>;
};

this is one of the first types I add to any @vercel #nextjs project. Using it ensures that authors of server routes declare the inputs the handler expects, making client-side code easier to write.