remove overlay when no animation/class is used

[mshwery]

use a timeout, or some other means to remove the overlay if no animation end event fires for fading out the image.

[thomas-lebeau]

In what case does it not fire?

An alternative is to keep the overlay in the DOM and give it display:none in the keyframe.
The advantage is that you have the overlay ready for next zoom.

[mshwery]

TBH I haven't tested that this actually is a bug, but wanted to leave a note that I should test what happens when there is no fade-out to trigger animation end.