Closing and opening a modal simultaneously causes a crash

[Joostb]

We just finished our migration to vue3. Unfortunately, we discovered a bug in portal-vue. I created a html-file reproduction of the bug, based on our use case.

portal-vue-bug-reproduction.html

Steps to reproduce:

1. Click the button
   • Content is rendered to the portal-target
2. Click the red button that appears
   • an error occurs in the console, the content is not removed from the portal

During testing i noticed that the nested "modal" components are necessary to trigger the bug