First of all. The arrows I drew in the pictures are virtual objects, not virtual images, as I first said. Sorry!

Yes it's a diverging lens. I tried the same app and it just doesn't seem right. The thing is that the app doesn't know what happens when you move the object past the lens, when it becomes virtual. That's what I think. If you look at the red ray it goes to the left, when light only goes to the right...

It looks like a mirror image of the diagram when the object is placed in front of the lens. Just move the object back and forth and see. It's the exact mirror image.

Anyway this kind of ray diagrams are better drawn on paper. I just can't get it...