Error thrown when using Vue Composition API in component library

[willtpwise]

I've noticed an issue with the Vue Composition API when used inside of a third party library.

The Vue Composition API throws an error when a component library (using the composition api) attempts to use one of the API methods (e.g. ref()).

[Vue warn]: Error in data(): "Error: [vue-composition-api] must call Vue.use(plugin) before using any function."

The consumer of the package using the Vue Composition API has already called Vue.use(CompositionAPI).

I've set up a reproduction of the issue below which should hopefully details the issue:
https://github.com/willtpwise/vue-comp-package

Related to:

• "x" get called outside of "setup()" error if you have different versions of vue-function-api #61
• Usage in component library #181

[posva]

This is the same problem as with linked packages (#228). The lib is using a copy of the library and it doesn't work

[willtpwise]

Thanks Posva. #228 helped solve the problem 👍