Keir Starmer is cocking this up (Image: Getty)Every time a teenager posted pictures of her self-harming online she would get messages encouraging her to cut deeper, to make it bleed more. She was told she wasn't doing it well enough and should do it better. Her social media feed was full of images of other people's self-harm injuries, with similar comments underneath those posts. And then one cold wintry day, she went on to the railway tracks at a station near her home. She died almost instantly when she was hit by a train. It was the first teenage suicide…