Enable Retrieving Username Claim from Userinfo Endpoint

backend/open_webui/utils/oauth.py

@@ -355,7 +355,11 @@ class OAuthManager:
             log.warning(f"OAuth callback error: {e}")
             raise HTTPException(400, detail=ERROR_MESSAGES.INVALID_CRED)
         user_data: UserInfo = token.get("userinfo")
-        if not user_data or auth_manager_config.OAUTH_EMAIL_CLAIM not in user_data:
+        if (
+            (not user_data) or
+            (auth_manager_config.OAUTH_EMAIL_CLAIM not in user_data) or 
+            (auth_manager_config.OAUTH_USERNAME_CLAIM not in user_data)
+        ):
             user_data: UserInfo = await client.userinfo(token=token)
         if not user_data:
             log.warning(f"OAuth callback failed, user data is missing: {token}")