Have you ever ran into this warning?

Warning: Can’t perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.

I bet this is the most common ReactJS newbie mistake... Forgetting to clean up your effects.

Stumbled over it again and here's how I fixed it: https://github.com/dimaip/calendar/commit/c20274917feff86af859f7252b717b84936ba865