<keep-alive> throws an error when used with in-DOM template

[NataliaTepluhina]

Version

3.0.0-alpha.4

Reproduction link

https://codesandbox.io/s/keep-alive-bug-yoyh1

Steps to reproduce

1. Create an app with in-DOM template with dynamic components
2. Put dynamic component within <keep-alive> tag
3. Try to switch between components

What is expected?

You should be able to change the component and component is expected to not to be destroyed when we switch to different component

What is actually happening?

On first component switch an error is thrown:

TypeError: parentComponent.sink.deactivate is not a function
    at unmount (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6780:40)

    at patch (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:5992:15)

    at patchBlockChildren (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6195:15)

    at processFragment (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6245:19)

    at patch (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6004:19)

    at componentEffect (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6439:19)

    at run (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:3773:22)

    at reactiveEffect (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:3755:18)

    at callWithErrorHandling (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:4436:38)

    at flushJobs (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:4990:11)

On all the subsequent attempts the error is different:

TypeError: Cannot read property 'parentNode' of null
    at parentNode (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:8551:34)

    at patchBlockChildren (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6191:21)

    at processFragment (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6245:19)

    at patch (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6004:19)

    at componentEffect (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:6439:19)

    at run (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:3773:22)

    at reactiveEffect (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:3755:18)

    at callWithErrorHandling (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:4436:38)

    at flushJobs (https://unpkg.com/vue@3.0.0-alpha.4/dist/vue.global.js:4990:11)