feat(error-format): Assign our own pointer only if there is no existing

Author: koriaf

rest_framework_json_api/utils.py

@@ -429,9 +429,8 @@ def format_error_object(message, pointer, response):
         if is_custom_error:
             if "source" not in message:
                 message["source"] = {}
-            message["source"] = {
-                "pointer": pointer,
-            }
+            if "pointer" not in message["source"]:
+                message["source"]["pointer"] = pointer
             errors.append(message)
         else:
             for k, v in message.items():