Smartmenus is not a function

I'm running into major problems due to the following console error:

VM2013 jquery.min.js:2 jQuery.Deferred exception: jQuery(...).smartmenus is not a function TypeError: jQuery(...).smartmenus is not a function
at themeMenu (https://mysite.com/themes/contrib/coffee_zymphonies_theme/js/custom.js?s...)
at HTMLDocument. (https://mysite.com/themes/contrib/coffee_zymphonies_theme/js/custom.js?s...)
at e (https://mysite.com/core/assets/vendor/jquery/jquery.min.js?v=3.7.1:2:27028)
at t (https://mysite.com/core/assets/vendor/jquery/jquery.min.js?v=3.7.1:2:27330)
at nrWrapper (https://mysite.com/page:5:16507) undefined