This week, ReadKit started crashing for me as soon as I opened it. No matter if I tried to refresh, click on a tab or open the preferences it crashed. I can only assume that it was something to do with my subscriptions that caused the error.
I decided to clear everything and start again in ReadKit, and the issue was solved.
To fix the issue:
Open Finder, then in the menu bar select
Go to folder... and paste in the following path:
Once that folder opens, rename
ReadKit.storedata.old and restart ReadKit. All your subscriptions should be missing, but ReadKit should no longer crash. Reconnect all your services, and you're good to go.