Open opening an empty folder through HUB gives an impression of opening the Editor by showing Unity Splash, however, it doesn't open it.

Steps to Repro:
1. Create an Empty Folder
2. Launch HUB
3. Open empty folder

Actual Result:
1. Unity Splash screen appears
2. The editor doesn't launch

Expected Result:
Some error should be given if opening an invalid Project or invalid Project should not be selected

Occurring with:
HUB 1.4.0

Environment:
Windows and Mac