[Vuejs]-Why does vuetify in my project break when used in .js file vs .vue file

So turns out it wasn’t working because I had two versions of Vue installed. I removed the second version (which was an older version of Vue) and then importing Vuetify in index.js worked fine. I’m still not sure why Vuetify worked with duplicate versions of Vue when included in App.vue and not when in index.js, but removing that second instance of Vue fixed this problem for me.