https://github.com/earwig/copyvios/issues/25
Plagiabot's API handles internal errors like this: http://tools.wmflabs.org/eranbot/plagiabot/api.py?action=suspected_diffs&page_title=%D0%9D%D0%B8%D0%BA%D0%BE%D0%BB%D1%8C%D1%81%D0%BA%D0%B8%D0%B9%20%D0%9D%D0%B8%D0%BA%D0%BE%D0%BB%D0%B0%D0%B9%D0%98%D0%B2%D0%B0%D0%BD%D0%BE%D0%B2%D0%B8%D1%87&report=1
Add a check and handle errors on the copyvios end to handle this scenario.
Bonus points: file an issue on plagiabot.