Steps To Reproduce:

1. Create a new project
2. Import ProBuilder package from Windows> Package Manager
3. Tools> ProBuilder Window
4. Select Directional Light in the Inspector and Select "Export' in the ProBuilder window

Expected Result: No mesh select message appears in the Scene window

Observed Result: Export asset window appears which doesn't do anything

Reproducible On Package version: 4.1.2, 4.0.2

Not Reproducible On: 3.10.1

Checked On Unity Version: 2020.1.0a15, 2019.3.0f2, 2019.1.014f1

Environment: Windows and Mac