Transition `out` leaves invisible elements in the DOM after reassignment

[csangonzo]

Describe the bug
The bug comes out then I use the out:<any_svelte_transition> in a list of items ({#each}...{/each}).
When I reassign the array that I loop through with each and the data comes from a Promise and the data 'arrives' earlier then the out animation finishes, the previous data won't get removed from the DOM, it's going to be hidden, but it takes up the space unnecessarily.

To Reproduce
To reproduce try the example in this repl: https://svelte.dev/repl/7163b83de9b74b7b9d2a84560b73f6bd?version=3.36.0

• Click on filter and you can see the overflow is still there and if you ispect the list container, you can see the previos data in there.

Expected behavior
The items should disappear from the dom also and should not take up the space.

• Your browser and the version: Firefox, Edge, Chrome
• Your operating system: Windows, Debian
• Svelte version: 3.36.0
• Rollup

Severity
Somewhat annoying when trying to filter an array of products and want to do it with a smooth animation.

[Kapsonfire-DE]

I can confirm this bug. Tested a bit around and this happens when you modify during transition. See also #6152

[jrmoynihan]

I also can confirm this bug. It's actually layout-breaking because the "empty" leftover nodes are still getting counted as child elements in my grid layout. You can also repeat this infinitely to get many more leftover nodes if you can trigger the unmount/destroy before the transition finishes.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been closed as it was previously marked as stale and saw no subsequent activity.

[csangonzo]

.