Update src/pyop/provider.py

Improve initialisation of extra_id_token_claims

Co-authored-by: Ivan Kanakarakis <ivan.kanak@gmail.com>

Author: Zoopa

src/pyop/provider.py

@@ -446,8 +446,7 @@ def _do_code_exchange(self, request,  # type: Dict[str, str]
         if refresh_token is not None:
             response['refresh_token'] = refresh_token
 
-        if extra_id_token_claims is None:
-            extra_id_token_claims = {}
+        extra_id_token_claims = extra_id_token_claims or {}
 
         if self.stateless:
             extra_id_token_claims_in_code = self.authz_state.get_extra_id_token_claims_for_code(token_request['code'])