Bone name is accepted as blank/empty in the "Skinning Editor", refer attached screenshot

Steps to repro:
1. Create a new project
2. Window > Package Manager > 2D Animation(4.0.0) > Install
3. Import Sample Project Under 2D Animation Package
4. Asset > Unity Technology > 2D Animation > Sample > Sprite > Boris
5. Open Sprite Editor > Skinning Editor
6. Enable Visibility of Panel
7. Edit Bone name and give the blank input to name

Actual Result:
Blank/empty input accepted as a Bone label

Expected Result:
Blank input should not be accepted

Reproducible on:
2020.1.0a14, 2019.3.0f1

Note: 2D animation package 3.0.2 is introduced in unity 2019.3.0a10

Package Found version: 4.0.0, 3.0.8, 3.0.5, 3.0.2

Environment:
Windows 10 & macOS 10.14