Package Manager lets some packages to be imported when everything in the package is deselected while other packages have the “Import” button greyed out

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Download the FPS Microgame package
3. Open the Package Manager (Window > Package Management > Package Manager)
4. Select "My Assets"
5. Import the FPS Microgame package
6. Deselect everything in the package by pressing the "None" button
7. Click the "Next" button
8. Repeat step 6
9. Observe the Import Unity Package window

Actual results: Unity Package window allows the package with nothing selected to be imported

Expected results: The "Import" button is greyed out and cannot be clicked

Reproducible with versions: 6000.0.60f1, 6000.2.8f1, 6000.3.0b6, 6000.4.0a2

Tested on (OS): MacOS Silicon Sequoia 15.6.1