Fix type discrimination for non-overlapping content types

[illright]

Changes

Fixes #1609

How to Review

I've added a new kind of test — Vitest type test, to verify the correctness of this solution.

Checklist

• Unit tests updated
• docs/ updated (if necessary)
• pnpm run update:examples run (only applicable for openapi-typescript)

[changeset-bot]

🦋 Changeset detected

Latest commit: 7f75fa9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
openapi-typescript-helpers	Patch
openapi-fetch	Patch

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[drwpow]

This is great, thank you!

If you could fix the linting error, and add a patch changeset (see comment), I’d be happy to merge. The tests pass locally for me; there seems to be an issue in CI right now that’s unrelated to your PR.

[JrSchild]

Hi @illright. Does this also fix the issue where both data and result can not infer correctly to their respective types after an if check?

const dataRes = await GET('/');

if (dataRes.data !== undefined) {
  // dataRes.data is never 
  console.log(dataRes.data);
}

[illright]

@JrSchild hard to say, I would need to see your openapi schema as well. Feel free to check out this branch and try it out for yourself

[illright]

@drwpow is it ready to go?

[drwpow]

Ah thanks for the poke! Looks great and will merge; CI tests are currently experiencing an issue that I’ll fix this week.

[drwpow]

Released in the latest version of openapi-fetch. Thanks again!