The tragic death of 19-year-old Petaluma, Calif., resident Alyssa Byrne raises a couple of issues, but that she appeared to be alone when she died is a critical one for us.We don't want to be seen as lecturing or chiding, especially when dealing with the death of a young person who was by all accounts beloved in her community.But we hope that Carson Valley parents are using this incident as a teaching moment for their children.We know that young people will go out into the world. They will experience adventures that may at times put them in harm's way.There's nothing …