Such sad news.
As others have said we 'know' there are risks, but you don't really expect it to happen. I think if we did focus heavily on the risks then we, perhaps, wouldn't go through with it. We have to trust our surgeons and, if they think the risk is low or worth taking, then we have to put our faith in them.
Interestingly, I watched a programme several weeks ago about teenagers undergoing wls. A comment was made about the mortality rate being 1 in 150. This made me wonder if, although the risk is still there, due to whatever reasons, the surgery is becoming slightly safer.
This is no consolation, though, to this poor lady and her family and friends who have experienced such a sad loss. RIP