check for empty vector before accessing .back()
check for empty vector before accessing .back()

morbozoo/sonyHeadphones,2666hz/Cinder,morbozoo/sonyHeadphones,sosolimited/Cinder,sosolimited/Cinder,morbozoo/sonyHeadphones,2666hz/Cinder,morbozoo/sonyHeadphones,2666hz/Cinder,sosolimited/Cinder,sosolimited/Cinder,2666hz/Cinder