Fix next button when reaching one of the sources' last page (fix #1301)
Fix next button when reaching one of the sources' last page (fix #1301)

Bionus/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber