Against the car going airborne like that, or as we call it on our local track "having a LeMans-Moment", there is not much you can do. As you said, you ran over a twig or something. It happens and usually you land on the wheels or in the grass, then you are lucky. You really just had a moment of bad luck, really bad luck in this case with all the damage but there isn't really anything to do against it.
I myself, when I am done marshalling I usually look on the track for twigs and debris and clean a little in my section. But with the wind doing his own thing, there is not much you can do...