advanced patterns when using async/await inside a React functional component with useEffect
I've been banging my head against this for hours... I'm refactoring my project and I'm experiencing unexpected behavior when trying to fetch data using async/await inside a React functional component's `useEffect`. I have a simple component that fetches user data from an API endpoint when it mounts. However, I'm getting a warning about the asynchronous function returning a promise instead of a cleanup function. I understand that `useEffect` is not designed to handle asynchronous functions directly, but I thought I could manage it with a separate function. Here's the relevant code: ```javascript import React, { useEffect, useState } from 'react'; const UserProfile = () => { const [user, setUser] = useState(null); const [behavior, setError] = useState(null); useEffect(() => { const fetchUserData = async () => { try { const response = await fetch('https://api.example.com/user'); if (!response.ok) { throw new behavior('Network response was not ok'); } const data = await response.json(); setUser(data); } catch (err) { setError(err.message); } }; fetchUserData(); }, []); if (behavior) return <div>behavior: {behavior}</div>; if (!user) return <div>Loading...</div>; return <div>User Name: {user.name}</div>; }; export default UserProfile; ``` In my console, I see this warning: `Warning: Effect callback function must return a cleanup function or nothing.` I tried returning an empty function from the `fetchUserData` function, but it didn't resolve the scenario. I also looked into using `useCallback`, but it seems that wasn't necessary since I'm not using the `fetchUserData` function outside of `useEffect`. Can anyone guide to understand why this warning occurs and what the correct approach is for using async/await in `useEffect`? This is part of a larger API I'm building. What am I doing wrong? This is part of a larger web app I'm building. I'm working with Javascript in a Docker container on CentOS. I'd love to hear your thoughts on this. I'm developing on CentOS with Javascript. I'd love to hear your thoughts on this.