Mobile Menu no longer working

The mobile menu on the site is no longer working and I notice when it’s clicked on there is a js error. I just don’t know enough on how to fix it. I tried to disable plugins and it doesn’t fix itself. I also tried to change the theme but no other standard theme gives the hamburger menu so it’s not a viable test. Can anyone guide me on this? It’s a huge issue for this client going into Christmas.

The page I need help with: [log in to see the link]