Steps to reproduce:
1. Create new Unity project
2. Install Entities and Entities Graphics package via Package Manager
3. In Hierarchy create a New Sub Scene
4. Select “New Sub Scene” GO in Hierarchy window
5. In Inspector window > Sub Scene Component select “Scene Asset”
6. In “Select Scene Asset” window select “New Scene” Scene
7. In “convert to Sub Scene” pop-up select “Convert”
8. Back in Inspector window > Sub Scene > Open SubScenes select “Close” button
9. In “Scene(s) Have Been Modified” pop-up press “Save”
10. Observe the Console window

Actual results: “[Worker0] InvalidOperationException: Cannot create a new scene additively with an untitled scene unsaved.” error is throw in the Console window

Expected results: No errors are thrown in the Console window

Reproducible with versions: 6000.0.66f2, 6000.3.8f1, 6000.4.0b8, 6000.5.0a6

Tested on (OS): macOS Silicon Tahoe 26.2 (M1)