How to reproduce:
1. In Unity Hub, create and open a new Unity project
2. In Unity Hub, try to open the project that is already open
3. Observe the Unity Hub
Actual result: Unity Hub closes
Expected result: Unity Hub gives a warning that the project is already open
Reproducible with: 3.16.3
Reproducible on: Ubuntu 25.10 (by user), Windows 11
Not reproducible on: No other environments tested