onAfterClose prop called on unmount even if modal is closed

[gdostie]

Summary:

The onAfterClose prop is called when unmounting the ReactModal even if the modal is not opened while the unmount occurs.

Steps to reproduce:

1. Render a ReactModal with an onAfterClose callback.
2. Unmount the ReactModal in some way (I my example I navigate elsewhere using react-router-dom)
3. Notice the function provided to onAfterClose prop being called each time the ReactModal unmounts.

Expected behavior:

Given the name of the prop, I would have expected the callback prop to be called only when the modal went from opened state to closed state.

Link to example of issue:

https://codesandbox.io/s/54xl6lz32n

Additional notes:

[gdostie]

👋 Friendly ping for someone to take a look at the PR 🙏