How to correctly type .json() when I add an error handler plugin

[predragnikolic]

Hello,

First here is stackblitz example https://stackblitz.com/edit/vitejs-vite-wr3soc?file=src%2Fmain.ts if you want to try help out.

I have the following fets code:

import { ClientPlugin, NormalizeOAS, OASOutput, createClient } from 'fets';

export type API = NormalizeOAS<OpenAPI>; // OpenAPI is defined in the stackblitz example, 
// in short OpenAPI contains a get /test endpoint, that can return '200', '400', '418' status codes, and each status code returns a different json object

// Add plugin to throw an error when the response is not OK.
function useErrors(): ClientPlugin {
  return {
    async onResponse({ response }) {
      if (!response.ok) throw await response.json();
    },
  };
}

export const fets = createClient<API>({
  endpoint: 'http://localhost:3666/api',
  plugins: [useErrors()], 
});
// ...

The issue

lets look at this code:

let response = await fets['/test'].get().json();

because I added the useErrors hook, I expect the following:

// I would like the `response` only to contain the type for status code 200, which is:
// {ok: boolean}
//
// but I get response with objects when the status code is not ok:
// {ok: boolean} | {errorKey: "...", data: {}} | {errorKey: "...", data: {...}}
//
// How can I type assure await fets['/test'].get().json(); to return type {ok: boolean}
let response = await fets['/test'].get().json();

// Here fets is able infer the type 200 correctly,
// the type only contains: {ok: boolean}
type TestResponseStatusOk = OASOutput<API, '/test', 'get'>;

what should I do get the expected type?

[predragnikolic]

Huh, I tried to override the OASResponse file, but without success

//fets.d.ts
import "fets"

declare module "fets/typings/client" {
	import { OpenAPIDocument } from "fets/typings/client/types"
	export type OASResponse<TOAS extends OpenAPIDocument, TPath extends keyof TOAS['paths'], TMethod extends keyof TOAS['paths'][TPath]> = {
		[TStatus in keyof OASStatusMap<TOAS, TPath, TMethod>]: TypedResponse<
			FromSchema<
				OASJSONResponseSchema<TOAS, TPath, TMethod, 200>
			>,
			Record<string, string>,
			200
		>;
}