Prettier error handling

_usage.ts

import { sayHello } from "./sayHello.ts";

const [str, isErr, err] = await sayHello();

asyncTry.ts

/**
 * Given a function, return `[result, isErr, err]`.
 *
 * Contains `isErr` to safely infer truthiness of types when checking for issues
 * without having to resort to error wrapping or `instanceof` checks.
 */
export const asyncTry = <Fn extends (...args: any[]) => any>(
  /**
   * The function to wrap.
   */
  fn: Fn
) => {
  return async (...args: Parameters<Fn>) => {
    try {
      const ret = await fn(...args);
      return [ret, false, undefined] as [
        result: Awaited<ReturnType<Fn>>,
        isErr: false,
        err: undefined
      ];
    } catch (err: unknown) {
      return [undefined, true, err] as [
        result: undefined,
        isErr: true,
        err: unknown
      ];
    }
  };
};

sayHello.ts

export const sayHello = asyncTry((name: string) => {
  return `Hello, ${name}`;
});