1. clone this repo
2. install package in "app" and "plugin" project
3. cd plugin && npm link
4. go back into "app" directory => npm link plugin
5. npm run serve and open your favorite browser

Using vue-class-component you can't access $vuetify in the external plugin, but using pure js object, it works.

HelloWorld Component is working HelloWorldTS can't see $vuetify

Vuetify is used here as an exemple. You'll have the same issue with every plugin.