Update src/nwp500/api_client.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: eman

src/nwp500/api_client.py

@@ -169,10 +169,13 @@ async def _make_request(
                         )
                         try:
                             # Try to refresh the token
-                            if self._auth_client.current_tokens:
+                            if self._auth_client.current_tokens and getattr(self._auth_client.current_tokens, "refresh_token", None):
                                 await self._auth_client.refresh_token(
                                     self._auth_client.current_tokens.refresh_token
                                 )
+                            else:
+                                _logger.error("No refresh_token available for token refresh.")
+                                raise AuthenticationError("No refresh_token available for token refresh.")
                                 # Retry the request once with new token
                                 return await self._make_request(
                                     method,