Description is shown as null if data-description is empty

[ghost]

As it says - in the info bar there is text "null" if image data-description is empty.
Personally I have very little experience with js, but I was able to find a simple solution - in custom image object function change
description: img.data('description')
to
description: img.data('description') || ''
(maybe same thing should be done with titles?)
thanks for a nice gallery!