Uncaught Promise error in concurrent mode

[pejman1]

I would appreciate if someone could help me in this issue. Whenever I use react-pouchdb/concurrentmode I got Uncaught Promise error and 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.

could somebody send me an example code of concurrent mode