Animation on close not properly triggered with delay

[nealoke]

Summary:

Steps to reproduce:

1. Open the codesandbox
2. Close the modal by clicking the background
3. See no animation when closing

Also when I do this in my app and record it, you see that it adds the class but not for the delay (400ms) specified as it does with the after open

Expected behavior:

Should add a delay to the actual unmounting (working) and add the class on the beginning of the delay for animation. Currently it waits for the delay, adds the class and directly unmounts

[rawatnaresh]

In case somebody else having the same issue this might help.