error when patch with root level comment

[a631807682]

Version

3.0.0-alpha.11

Reproduction link

https://codepen.io/a631807682/pen/BaoBwPY?editors=1011

Steps to reproduce

1. Open the link and click the button.
2. See console.

What is expected?

work fine

What is actually happening?

throw error

vue.global.js:4989 TypeError: Cannot read property '_vtc' of null
    at patchClass (vue.global.js:10060)
    at patchProp (vue.global.js:10277)
    at patchElement (vue.global.js:7284)
    at processElement (vue.global.js:7187)
    at patch (vue.global.js:7130)
    at patchBlockChildren (vue.global.js:7357)
    at processFragment (vue.global.js:7399)
    at patch (vue.global.js:7126)
    at componentEffect (vue.global.js:7594)
    at Object.reactiveEffect [as update] (vue.global.js:4080)

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ref #904