Vanilla enum renderer should store undefined instead of empty string

[sdirix]

Describe the bug

When selecting the empty option in React Vanilla's enum renderer, an empty string is stored instead of undefined. This is unexpected and also leads to validation errors.

Expected behavior

Undefined should be stored instead of the empty string when an enum is "unselected".

Steps to reproduce the issue

1. Run the person example
2. Select a nationality
3. Unselect nationality

Screenshots

No response

In which browser are you experiencing the issue?

102.0.5005.115

Framework

React

RendererSet

Vanilla

Additional context

No response