added extra error counter so user knows how many images were downloaded, how many downloads failed because image doesn't exist or the external resource cannot be reached
added extra error counter
so user knows how many images were downloaded, how many downloads failed because image doesn't exist or the external resource cannot be reached

SlovakNationalGallery/web-umenia-2,rastislav-chynoransky/web-umenia-2,rastislav-chynoransky/web-umenia-2,SlovakNationalGallery/web-umenia-2,SlovakNationalGallery/web-umenia-2,rastislav-chynoransky/web-umenia-2,SlovakNationalGallery/web-umenia-2