setting overflow: hidden on the html, body and then pressing keyboard key throws

[Maximilianos]

Error thrown:

Uncaught TypeError: Cannot read property 'clientHeight' of undefined
webpack:///./~/smoothscroll-for-websites/SmoothScroll.js:401

Use case:
I have smoothscroll active on a given page
I have a modal script that when it opens will set the html & body to overflow:hidden;
Problem:
When a key is pressed on the keyboard with the modal open the aforementioned error is thrown