query error typing help

[zhihengGet]

hello, thanks for the help

i use custom queryFn and i typed the query result as

Promise<
  | {
      data: {};
      error?: undefined;
    }
  | {
      data?: undefined;
      error: { text: string; statusCode: number };
      meta?: { request: Request; response: Response };
    }
>

the thing is that i when i access result.error.text i keep getting SerializedError does not have text

how i remove this SerializedError from ts

[phryneas]

There is always the possibility of a SerializedError since we cannot "read" your code and guarantee that it doesn't just throw an exception at some point - and every unhandled error would be handled as a SerializedError.

It's kinda how in TypeScript, in a catch block, the error is either any or unknown, but never something specific until you start making assumptions on it.

So you will probably need to write some Type Guard function to make sure it is what you expect.

[bggolding]

This is a really common question that comes up for me a lot. While I know how to write a type guard, I never know what the correct test to use for the type guard is, which types I should be checking against in RTK or whether there’s pre-existing support in the library for this. Could we perhaps get an example?

I find handling and reporting errors from queries to be really difficult. I wind up in a mess of tests whether there are attributes on the error object and hope that I’ve managed to get the right ones together so that the error appears coherent. When I contrast this with handling errors from a mutation using (say) .catch((error) => setErrorMessage(error.data.message)) I just reckon this could be better.