How to reproduce:
1. Create a new project
2. In the Project view, select Create > Scripting and create a new .cs file
3. In the Project view, select Create > UI Toolkit > UI Document and create a new .uxml file
4. Select both (.cs and .uxml) files in the Project View
5. Drag & drop the two files selected to another directory
6. Observe the Inspector and the Console windows

Expected result: No errors in the Console window and the Inspector window’s behavior hasn’t changed
Actual result: Errors appear in the Console window and the Inspector’s window turns black

Reproducible with: 2023.3.0a9, 6000.0.53f1, 6000.1.11f1, 6000.2.0b9, 6000.3.0a1
Not reproducible with: 2021.3.53f1, 2022.3.63f1, 2023.3.0a8

Reproducible on: Windows 11
Not reproducible on: No other environments tested