watcher runs while the component is being unmounted

[posva]

Version

3.0.0-beta.23

Reproduction link

https://jsfiddle.net/w54fzat2/

Steps to reproduce

Click on toggle multiple times

What is expected?

no logs

What is actually happening?

logs at every toggle

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Coming from #1525 (comment) and vuejs/router#374

I think it would make more sense to not trigger the watcher while the component is unmounting. It would also be consistent with Vue 2 https://jsfiddle.net/7webxnam/.