Unmounted App cannot be mounted again

[vjcagay]

Version

3.0.0-beta.14

Reproduction link

https://codesandbox.io/s/busy-rgb-5j76y?file=/index.html

Steps to reproduce

1. Mount an app using the .mount(el) method
2. Unmount it using .unmount
3. Step 1

Also, if the app is already mounted and is mounted again the app unmounts.

What is expected?

App will just mount as expected.

What is actually happening?

Vue logs in the console:

[Vue warn]: App has already been mounted. Create a new app instance instead.

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Trying make Vue 3 run on Storybook as an experiment

[yyx990803]

This is expected. If you need to remount the same app, put your app creation logic in a factory function and call it again to create a new app instance.