Typescipt error handling

errorHandlingGoStyle.ts

/* Return tuple types, with a nullable error component just like Go */
/* meta: Typescript 3.9.5 */

type Err = Error | null;

async function getUser(): Promise<[string, Err]> {
  try {
    const res = await fetch('/me');
    const data = await res.json();
  
    return [data, null];
  } catch (err) {
    return ['', err];
  }
}

(async () => {
  const [user, err] = await getUser();
  if (err !== null) {
    console.error(err);
  
    return;
  }

  console.log(user);
})();

errorHandlingRustStyle.ts

/* Return Result/Option types just like Rust */
/* meta: Typescript 3.9.5 */

type Result<T> = ({ success: true } & T) | { success: false; err: Error };

async function getUser(): Promise<Result<{ user: string }>> {
  try {
    const res = await fetch('/me');
    const user = (await res.json()) as string;

    return { success: true, user };
  } catch (err) {
    return { success: false, err };
  }
}

(async () => {
  const result = await getUser();

  if (!result.success) {
    console.error(result.err);

    return;
  }

  console.log(result.user);
})();