Steps to reproduce:
1. Create new Unity project
2. Open Package Manager window
3. Install Behaviour package (com.unity.behavior)
4. In Project window create Blackboard (Create > Behaviour > Blackboard)
5. Open Blackboard window
6. Create any Variable by pressing “+” at the top right (GameObject for example)
7. Delete selected “New GameObject” name and press Enter
8. Observe the Variable 

Actual results: A Variable with no name can be created in the Blackboard
Expected results: A Variable with no name should not be allowed to be created, a tooltip with warning should be thrown, that Variable must have a name

Reproducible with versions: 1.0.13 (6000.0.62f1, 6000.2.10f1, 6000.3.0b9, 6000.4.0a4)

Tested on (OS): Ubuntu 22.04, macOS Silicon, Tahoe 26.0 (M1)