[REQ] Feature Request Description

Created by: javier-garcia-meteologica

Is your feature request related to a problem? Please describe.

In javascript/typescript throwing anything but an error is considered an antipattern. Only errors should be thrown because:

• Only errors can provide a reliable stacktraces
• Makes error handling easier, since 99.99% of caught "things" will have a common interface { message: string }.

Right now typescript-fetch throws a bare Response which is undesirable. https://github.com/OpenAPITools/openapi-generator/blob/60b29e1f8e267e90d4d81f30d3fb3fe69161e59b/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache#L38-L42

Describe the solution you'd like

Typescript-fetch should throw a custom error in which the response is just a property, just like it does with RequiredError. https://github.com/OpenAPITools/openapi-generator/blob/60b29e1f8e267e90d4d81f30d3fb3fe69161e59b/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache#L104-L109

E.g.

        const response = await this.fetchApi(url, init);
        if (response.status >= 200 && response.status < 300) {
            return response;
        }
        throw new ResponseError(response, 'Response returned an error code');

...

export class ResponseError extends Error {
    name: "ResponseError" = "ResponseError";
    constructor(public response: Response, msg?: string) {
        super(msg);
    }
}