Crash with slot + async component

Vue version

latest

Link to minimal reproduction

play.vuejs.org

Steps to reproduce

<template>
  <div>
    <div>
      <slot name="prepend"></slot>
      <Dummy v-if="loading" title="needs to be async and resolve slowly" />
      <!-- comment or component -->
    </div>
  </div>
</template>

And then toggle both slot and loading until it crashes. See reproduction in the playground.

What is expected?

It should not crash.

What is actually happening?

can't access property "__vnode", el is null