Type narrowing for data after checking error

[y-hsgw]

Hi,

I'm currently using urql and encountered a situation where I couldn't narrow down the type of data after checking error. Here's an example:

import { registerUrql } from '@urql/next/rsc';

const makeClient = () => {
  ...
};
const { getClient } = registerUrql(makeClient);

export default async function Home() {
  const { data, error } = await getClient().query(PokemonsQuery, {});

  if (!error) return null;
  
  console.log(data); // type is object | undefined  

  return ...
}

Even though I've checked the error and ensured the code won't run when error is undefined, the type of data remains object | undefined.

Would it be possible to narrow the type of data to just object in this case?

export default async function Home() {
  const { data, error } = await getClient().query(PokemonsQuery, {});

  if (!error) return null;
  
  console.log(data); // type is object

  return ...
}

I may not fully understand the behavior of this library, so I would appreciate any clarification or guidance on whether this is possible.

Thank you for your help!

[y-hsgw]

Proposed by #3750