setState After Unmount

Updating component state after the component has already unmounted.

📋 Demo Instructions

1. Click "Start Test" to begin the async operation
2. Then navigate away (use Back button) before it completes
3. Wait 5-10 seconds for the error to be captured
4. Go to Dashboard → Performance Monitoring
5. Click "Fix with Carla" on the error
6. Review the generated PR

💻 Buggy Code

// Buggy Code
useEffect(() => {
  fetch('/api/data')
    .then(response => response.json())
    .then(data => {
      setData(data); // Error if component unmounted
    });
}, []);
// Warning: Can't perform a React state update on an unmounted component

🔴 Error Log