Codepen error

[Vac1911]

This imbedded codepen is producing an error.

Codepen: https://codepen.io/team/Vue/pen/76e344bf057bd58b5936bba260b787a8
Docs Location: https://v3.vuejs.org/guide/transitions-enterleave.html#cp_embed_76e344bf057bd58b5936bba260b787a8

Google Chrome - Version 88.0.4324.104 (Official Build) (64-bit)

[skirtles-code]

I've done some preliminary investigation.

It seems this worked in 3.0.3 but is broken in 3.0.4 and 3.0.5.

Wrapping the <slot> in another element, such as a <div>, and moving the v-if to that element fixes it. However, that shouldn't be necessary.

filterSingleRoot is being passed null for its children argument. This comes from vnode.children in getChildRoot and the node that fails is the <img>. It isn't immediately clear to me why it needs to check the children of the <img> but either it needs to handle the null or the children need to be [].

I experimented a bit and it seems that the same problem can be reproduced with any empty element, it doesn't have to be an <img>. A empty <div> gave the same error. Putting any content in the <div> was enough for the error to go away.

[NataliaTepluhina]

@Vac1911 thank you for reporting this! I've fixed a codepen with @skirtles-code recommended solution as a workaround.

@skirtles-code do you think this is rather a bug than a feature? Should we open an issue on core repo?

[skirtles-code]

Done.

Closing this for now but we should probably switch it back once the bug is fixed.