Environment

Vuetify Version: 3.6.14
Vue Version: 3.5.0-alpha.5
Browsers: Chrome 127.0.0.0
OS: Windows 10, Linux

Steps to reproduce

• Create Vuetify with defaults configuration, setting the attach property of VMenu to a custom element instance.
• Add a VMenu and open it.

Expected Behavior

The menu opens normally.

Actual Behavior

Maximum call stack size exceeded is thrown and the menu does not open.

Reproduction Link

https://play.vuetifyjs.com/#...

Other comments

It might be that mergeDeep utility used by the defaults composable is not able to merge objects with circular references.

While a string selector can be used for the attach property of VMenu, it does not work within the Shadow DOM. Document selectors cannot reach shadow elements, so it is necessary to pass an element instance in these cases.