In the bike world, the other people (cars or bikes) are just as big of an issue or danger as yourself.
RIP indeed.
As far as
She low sided out of a corner and the rider behind could not avoid hitting her"
Odds are that the rider wasn’t experienced enough to avoid it or was in mental shock to do a serious evasive maneuver in split second decision. If the impact was severe enough to kill her, she likely already stopped sliding while the rider behind her was still at full speed so speculating, there was some time to avoid. Bikes aren’t like a car and since they occupy a very small area on the road it’s easier to avoid a target than in cars.
I’d be more interested in where this happened and how she didn’t end up in the run off area before getting hit.