Uncaught TypeError: Cannot read property 'top' of undefined – offset error

I’m helping a friend out with a site and having issues with the fading nav header on scroll. It works on some pages, but on others there is a Javascript error – Uncaught TypeError: Cannot read property ‘top’ of undefined

All of the pages load the same JS files, so I can’t understand why it would work on some, but not others. Links are below

It works here https://www.notedcontent.com/home/

It doesn’t work here https://www.notedcontent.com

Any thoughts or ideas, would be greatly appreciated. Just an FYI, the theme is Bridge. Maybe someone has had a similar problem before.