This is a repeatable bug:
1. search for something from the newznab tab or from omgwtfnzbs search tab
2. right click and either "add to queue" or "add to queue paused"
3. when dialog box appears asking Enter Name etc, press cancel
Another dialog box appears with red X and says "List index out of bounds (0)" to which you can only press OK
Only tested on latest 0.43.0.1 - Windows 10 Pro x64, 8GB RAM
Nothing recorded in the log to indicate the error.
Please let me know if you require further information.