"XmlSchemaException" error is thrown and asset does not get created when creating UI Document after AI Assistant has been installed

Steps to reproduce:

1. Create a Unity project
2. Click the "AI" button
3. Click "Agree and install Unity AI"
4. Once installed, right-click in the Project window
5. Select Create > UI Toolkit > UI Document (UXML)
6. Observe the Console

Actual results: "XmlSchemaException: The simpleType 'Unity.AppUI.UI:VariantType' has already been declared." error and the asset does not get created

Expected results: Asset gets created with no errors

Reproducible with versions: 6000.4.0a1, 6000.4.0b11, 6000.5.0a8
Not reproducible with versions: 6000.3.0a6, ** 6000.3.11f1

 
Tested on (OS): Windows 11

Notes:

• Issue reproduces for the first time when trying to create UI Document
• For regression testing, in earlier versions you might need to delete Generators package after installing AI Assistant to clear Console errors