Can't link email to anonymous user for OTP auth

[willsmanley]

OTP email verification is impossible to add for anonymous users. If you add an email it works as expected, but when you validate it, it always creates a new user with that email identity rather than attaching it to the anonymous user. Again, it will be orphaned.

For more context please review: #1111

[willsmanley]

Solved: instead of signInWithOtp you want to use:

await Supabase.instance.client.auth.updateUser(
   UserAttributes(email: 'someemail@email.com'),
);

signInWithOtp will actually make a new auth.users row instead of attaching an identity to the currently signed in anonymous user. This is a bit confusing and could be documented better, but updateUser definitely works great.