Allow typing the body of a RequestError response

[dcaldastp]

What problem are you trying to solve?

I want to type the response body of a RequestError. Currently because RequestError does not accept a generic it's impossible to type the underlying response body.

export declare class RequestError extends Error {
    code?: string;
    stack: string;
    readonly options: NormalizedOptions;
    readonly response?: Response;
    readonly request?: Request;
    readonly timings?: Timings;
    constructor(message: string, error: Partial<Error & {
        code?: string;
    }>, self: Request | NormalizedOptions);
}

A valid workaround at the moment is something like:

type MyErrorBodyType = { reason: string; code: number; metadata: any }

type MyRequestError = Omit<RequestError, 'response'> & {
  response: Response<MyErrorBodyType>
}

This way ☝️ the body would be typed properly.

Describe the feature

I would like to be able to inject a type to the Request, like so 👇

export declare class RequestError<T> extends Error {
    code?: string;
    stack: string;
    readonly options: NormalizedOptions;
    readonly response?: Response<T>;
    readonly request?: Request;
    readonly timings?: Timings;
    constructor(message: string, error: Partial<Error & {
        code?: string;
    }>, self: Request | NormalizedOptions);
}

whereby T is the type fo pass along to the respective response body.

Checklist

• I have read the documentation and made sure this feature doesn't already exist.