[MenuField] Re-opening menu while transition closed causes `classes` to be `undefined` (instead of default)

[techniq]

If you quickly click to re-open the menu while it's transitioning closed,classes within MenuItem will be set to undefined instead of default object/styles.

https://github.com/techniq/svelte-ux/assets/177476/a36c772d-0717-4494-8909-c4674aa288a0

• MenuField
• MenuItem

Within MenuField, If you don't pass classes to MenuItem or set it explicitly to undefined (<MenuItem classes={undefined} />), the issue does not present.

[techniq]

This also occurs if you click on the chevron toggle button to close a menu already opened. See https://github.com/techniq/svelte-ux/pull/155#issuecomment-1864652385 for some context.

Would be good to test with Svelte 5 to see if this is still an issue. For the chevon button issue, ultimately it would be nice if the menu was closed and not quickly re-opened. See issue #93