I have this weird issue where sometimes my javascript is not loaded and not a single error shows up in my console.

If I hard refresh (CTRL SHIFT R) and normal refresh sometimes my page loads with the correct functionalities and other times all are broken.

Why could this be?

And how do I begin to sort out the problem?

This page for example: https://partykoning.nl/stormbanen-huren/wipe-out-muur-huren

The orange buttons that say 'RESERVEER NU' should not open a new page but instead a small popup text. The large text below should be shortened with a button to read more.

It seems random as to when it works.

I've tried removing parts of my javascript to see where the issue lies but the problem stays.

Also a strange thing is when it loads correctly and everything works, I do get errors in my console, but these errors are old and are unrelated to this issue.

So when the javascript stops working I get 0 errors, when it works I get some unrelated old errors in my console.

What can I do?