'Horrible' is stretch.
Played some part in the penalty, but it was Storari's poor judgement that mainly caused the penalty, he had no business rushing out when Lavezzi was surrounded by 2 defenders. It was difficult for Lavezzi to shoot from there anyway.
2nd goal is definitely not his mistake, counter attack and he was trying to close down Pandev. If any, it's Caceres who should marked Hamsik.