Theo's preferred way of handling try/catch in TypeScript

try-catch.ts

// Types for the result object with discriminated union
type Success<T> = {
  data: T;
  error: null;
};

type Failure<E> = {
  data: null;
  error: E;
};

type Result<T, E = Error> = Success<T> | Failure<E>;

// Main wrapper function
export async function tryCatch<T, E = Error>(
  promise: Promise<T>,
): Promise<Result<T, E>> {
  try {
    const data = await promise;
    return { data, error: null };
  } catch (error) {
    return { data: null, error: error as E };
  }
}

I was getting an error inside of the tryCatch function. It was something like operation is not a function or something like that. So . execute solved it for me. Edit: - Though it is better to handle this in the tryCatch function. Edit 2: Drizzle has an interesting (at least to me) implementation where if you don’t await, it returns a builder. If you do await, it becomes a Promise. More info about [Thenables (MDN) ](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise#thenables) The issue was that I was calling operation(), which returned a builder, not a Promise. So if I’m not wrong, inside the tryCatch block, if I wrap the result with Promise.resolve, it should work. ```ts const query = new FakeQuery(['user1', 'user2']); // Treated like a builder console.log('Query object:', query); // Auto-executes on await const result = await query; console.log('Result:', result); ```

I was getting an error inside of the tryCatch function. It was something like operation is not a function or something like that. So . execute solved it for me. Edit: - Though it is better to handle this in the tryCatch function. Edit 2: Drizzle has an interesting (at least to me) implementation where if you don’t await, it returns a builder. If you do await, it becomes a Promise. More info about Thenables (MDN) The issue was that I was calling operation(), which returned a builder, not a Promise. So if I’m not wrong, inside the tryCatch block, if I wrap the result with Promise.resolve, it should work. ts const query = new FakeQuery(['user1', 'user2']); // Treated like a builder console.log('Query object:', query); // Auto-executes on await const result = await query; console.log('Result:', result);

So it's related to the fixes @nazarEnzo applied a few comments above, where he passed the promises to Promise.resolve method. I still haven't used the tryCacth function with any prisma promise yet, but when I do, I'll come back here if any issue arises.

FYI: My initial answer code wasn't actually working properly for synchronous operations, because the return was always a Promise. Now this is fixed by using custom isPromise utility (to support non-native promises). Promise.resolve().then() can totally be replaced with .then()

/**
 * Checks if the value is a Promise
 * @param value - The value to check
 * @returns True if the value is a Promise, false otherwise
 */
export function isPromise<T = any>(value: unknown): value is Promise<T> {
    return (
        !!value &&
        (typeof value === 'object' || typeof value === 'function') &&
        typeof (value as any).then === 'function'
    );
}

// ----------------
// Test
// ----------------

import prismaClient from 'database/prismaClient';

const userPromise = prismaClient.user.findFirst();

console.log(
    userPromise instanceof Promise, // false
    isPromise(userPromise) // true
);