How to reproduce:
1. Create a new Unity project
2. Select any Asset in the Project window
3. At the bottom of the Inspector, open the Asset Bundle Variant dropdown
4. Observe the results
Expected results: Adding the new Asset Bundle variant is not possible because the Asset is not added to the Asset Bundle
Actual results: It is possible to add an Asset Bundle variant which throws an error
Reproducible with: 6000.0.74f1, 6000.3.14f1, 6000.4.6f1, 6000.5.0b7, 6000.6.0a4
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested