advanced patterns with async/await in a nested Promise scenario in Node.js
I'm performance testing and I'm collaborating on a project where I've been banging my head against this for hours. I'm working with an scenario where my async/await logic isn't behaving as expected when dealing with nested Promises in Node.js. I have a function that retrieves user data from a database, and then for each user, it fetches their associated posts. My implementation looks like this: ```javascript const getUserData = async (userId) => { const user = await db.findUserById(userId); const posts = await getPostsByUserId(userId); return { user, posts }; }; const getAllUsersData = async () => { const users = await db.findAllUsers(); const usersData = []; for (const user of users) { const data = await getUserData(user.id); usersData.push(data); } return usersData; }; ``` When I call `getAllUsersData()`, it sometimes throws an behavior: `UnhandledPromiseRejectionWarning: behavior: want to read properties of undefined (reading 'id')`. I have verified that the `findAllUsers` function returns an array of users, and each user has a valid `id`. I suspect the scenario might be with how I'm handling the async calls in the loop. I've tried wrapping the `getUserData` invocation in a try-catch block, but it still fails intermittently, leading to unhandled promise rejections. Here’s what I’ve tried so far: - I’ve added console logs to check the output of `findAllUsers()` and ensured it’s returning the expected objects. - I ensured that `getPostsByUserId` is also an async function and properly returning data. - I've tried using `Promise.all()` instead of the for loop, but then I ran into issues with maintaining the order of results. I’m using Node.js version 14.17.0. Any insights on what might be going wrong or any suggestions for refactoring this to avoid the behavior would be greatly appreciated! For context: I'm using Javascript on Ubuntu. Any feedback is welcome!