$scopedSlots is empty until render()

[KaelWD]

Version

2.6.11

Reproduction link

https://codepen.io/kaelwd/pen/rNLNYGL?editors=1011

Steps to reproduce

Open the console

What is expected?

"ScopedComponent beforeMount" true to be logged

What is actually happening?

"ScopedComponent beforeMount" false

---

This was discovered in vuetify: vuetifyjs/vuetify#11533 (comment)

The real setup is a watcher on a computed property that depends on $slots. The watcher is called before mount to get an initial value, causing the computed property to be executed and return an incorrect value.

Minimal example with the watcher if that helps: https://codepen.io/kaelwd/pen/vYKYWbV?editors=1010

This works as expected in vue 3: https://codepen.io/kaelwd/pen/gOMOXoB?editors=1011

The bug seems to have existed since scoped slots were introduced in v2.1, but it wasn't a problem here until v2.6 when scoped slots started being used everywhere with v-slot

[shadowings-zy]

Hello, I fix this bug in PR #11726 .
In before mount, Vue2 will always create an empty object when init render. And in this PR, it will normalize scoped slots when parent vnode is not undefined.