Javascript error after capture screen

[fscheu]

Hi! I'm trying to include this app in my site.
I could installed but during testing I reach the page to capture screen and when I press next button the modal screen disappear and I get this error in the console:

Uncaught (in promise) TypeError: this.parent.node.className.replace is not a function
at f.cleanDOM (:8:16345)
at f. (:8:3804)
at Array.forEach ()
at f.calculateOverflowClips (:8:3374)
at new f (:7:29071)
at i (:7:12313)
at :7:12107

Could you help me?
Thanks in advance!