Flutter, Riverpod, OAuth2.

So I was trying to learn something new and productive and at the same time wanted to learn it with future perspective. So Flutter, but with appwrite. I mostly followed https://www.youtube.com/watch?v=XnxZLhtkFeg (skipping only the self hosted part in favour of cloud) and got email signup, login and saving users to DB to work.
Next I wanted to add signup via discord and figured, that would work a lot like login, but with the added user creation if none existed with the given id. here's the function in the controller
and the function in the api. I also added the snippet in the manifest.

When I click the button, a browser opens on discord.com and wants me to authorize the app, then shortly visits cloud.appwrite.io, then goes back to discord "Authorize". When I manually switch back to the app the debug-console says

W/OpenGLRenderer( 3609): Failed to initialize 101010-2 format, error = EGL_SUCCESS
E/OpenGLRenderer( 3609): Unable to match the desired swap behavior.```

the AuthUser gets created in appwrite console, as does a session, but the app won't navigate to home. 

As a second issue, I tried to run the app in web, too, but I believe the success & failure urls aren't optional in this case. passing "http:localhost" does not work here, but I cannot figure out which other url to provide here.

I am, as stated, quite the beginner with flutter, auth and basically all of this & I can only allocate limited leisuretime to try and understand this. So apologies for my glacial learningprowess, and thanks in advance @D5 (and everyone else) to look into this.