There is currently a known issue with Twitch linking in users' profiles. If you unlink Twitch, the error should go away and you should be able to play D1 again.
English
-
I've unlinked the d2 extension from my twitch so I'm not sure
-
According to your profile, you still have Twitch linked in there. If you go to your profile's Settings > Accounts & Linking > unlink Twitch should do the trick.