v-for with v-else does not work on <template>

[xPaw]

Version

3.0.0-rc.1

Reproduction link

https://jsfiddle.net/Ld492zqn/

Steps to reproduce

From what I gathered, in Vue 2 v-for is lower priority than v-else so it should work correctly, but updating to vue 3 makes this code no longer work.

I looked in the vue eslint plugin, and they didn't add a warning for this because it's expected to work: vuejs/eslint-plugin-vue#799 (comment)

What is expected?

The loop works correctly.

What is actually happening?

message (key) is undefined

[xPaw]

Changing template to div fixes the issue.

AST for template

AST for div

It's not generating _renderList