Type annotations improvement

[garyhe0780]

const { data, error } = await resend.emails.send({
    from: 'Acme <[email protected]>',
    to: ['[email protected]'],
    subject: 'Hello World',
    html: '<strong>It works!</strong>',
});

if (error) {
    return console.error({ error });
}

console.log({ id: data.id });

taking an example from https://resend.com/docs/send-with-nodejs, If you access id from data directly, ts will complain that 'data' is possibly 'null', and that's because of return type:

 async fetchRequest<T>(
    path: string,
    options = {},
  ): Promise<{ data: T | null; error: ErrorResponse | null }>

and I think it's not accurate because from the code we can know that data can not be null when error is null, and it can be changed like this:

export type SuccessResponse<T> = {
  data: T;
  error: null;
};

export type FailureResponse = {
  error: ErrorResponse
  data: null;
}

export type Result<T> = SuccessResponse<T> | FailureResponse;
async fetchRequest<T>(
    path: string,
    options = {},
 ): Promise<Result<T>>