Sonarr crashes when attempting to process a release

Sonarr version (exact version): 2.0.0.5322
Mono version (if Sonarr is not running on Windows):
OS: Win 7
Debug logs: https://pastebin.com/rMGTzanK
Description of issue:
Since yesterday, Sonarr has been unable to download anything. All of yesterday’s episodes are missed, and if I try to search auto or manual Sonarr will close/crash when it attempts to process any release.

Win 7________________________
Sonarr running locally (not as service)________________
Up to date (latest master)________________
No changes made to PC in at least the last month_____________

Since this log was taken, I have completely uninstalled Sonarr (manually removed all associated folders) reinstalled it and rebuilt the whole database, but the issue remains.
If I search for a missing episode, Sonarr will search, then start processing found releases. At a random point in the processing, it will stop and close.

Maybe something with this ridiculously small size?

19-7-3 06:20:50.3|Debug|AcceptableSizeSpecification|Item: Penn and Teller Fool Us S06E03 1080p WEB h264-TBS[rarbg], Size: -9223372036854775808 is smaller than minimum allowed size (259522560 bytes for 45min), rejecting.

Looks like it’s coming from Kat, I’d suggest disabling that indexer and see if the issue persists.

You know… That almost has to be it.

I believe it has fixed itself, in a sense…

I manually downloaded yesterday’s episodes, and just checked and it has automagically downloaded one of today’s by itself!

This does beg a question though… How did that happen, and should it have been able to crash the app…