So Starkana apparently list chapters that aren't published yet, in some sort of linkbait douchecanoetasticticity.
Added facility to detect when a invalid download link is present, and delete the relevant row from the DB.
This will /probably/ cause invalid items to be added, and then immediately removed continuously every time the system checks for new items, but fukkit, if starkana wants to have such bullshit in place, they deserve the extra scraping traffic.