fix: handle empty response in Freightcom shipment creation

- Add failsafe handling for empty responses to prevent errors in shipment ID extraction.
- Ensure deserialization fallback to empty JSON if response is missing.

Author: jacobshilitz

plugins/freightcom_rest/karrio/mappers/freightcom_rest/proxy.py

@@ -51,11 +51,11 @@ def create_shipment(self, request: lib.Serializable) -> lib.Deserializable:
         response = self._send_request(
                 path="/shipment", request=lib.Serializable(request.value, lib.to_json)
             )
+        response_dict = lib.failsafe(lambda: lib.to_dict(response)) or {}
+        shipment_id = response_dict.get('id')
 
-        shipment_id = lib.to_dict(response).get('id')
         if not shipment_id:
-            return lib.Deserializable(response, lib.to_dict)
-
+            return lib.Deserializable(response if response else "{}", lib.to_dict)
 
         # Step 2: retry because api return empty bytes if done to fast
         time.sleep(1)