Handle errors more declaratively without try catch

tryResult.ts

/* eslint-disable @typescript-eslint/no-explicit-any */
export type Result<T, E> = [T, undefined] | [undefined, E];

/**
 * Handle errors more declaratively without try catch.
 *
 * ```
 * try {
 *   const res = doSomething(30);
 * } catch (err) {
 *   console.log(err);
 * }
 * // becomes
 * const [res, err] = tryResult(doSomething)(30);
 * ```
 *
 * @param fn A throwable function to run.
 * @returns A wrapped function that returns a Result enumeration.
 */
export function tryResult<A extends unknown[], T>(
  fn: (...args: A) => T
): T extends Promise<infer R>
  ? (...args: A) => Promise<Result<R, NonNullable<unknown>>>
  : (...args: A) => Result<T, NonNullable<unknown>> {
  return ((...args: A) => {
    try {
      const result = fn(...args);
      if (isPromise(result)) {
        return result
          .then((val) => [val, undefined])
          .catch((err) => [undefined, err]);
      }
      return [result, undefined];
    } catch (err) {
      return [undefined, err];
    }
  }) as any;
}

function isPromise(value: unknown): value is Promise<unknown> {
  return value != null && typeof value === "object" && "then" in value;
}