fix: LSDV-5307: Import review and drafts from exported snapshots: Add…

… tests, little fixes (HumanSignal#4527)

fix: LSDV-5307: Import review and drafts from exported snapshots: Add tests and little fixes

label_studio/tasks/serializers.py

@@ -275,9 +275,8 @@ def _insert_valid_user_reviews(dicts, members_email_to_id, default_user):
         :return:
         """
         for obj in dicts:
-            email = obj.get('created_by', {}).get('email')
-            if email is None:
-                raise ValidationError(f"Object must have created_by field and it should contain dict with email")
+            created_by = obj.get('created_by', {})
+            email = created_by.get('email') if isinstance(created_by, dict) else None
 
             # user default user
             if email not in members_email_to_id:
@@ -301,8 +300,6 @@ def _insert_valid_user_drafts(dicts, members_email_to_id, default_user):
         """
         for obj in dicts:
             email = obj.get('user')
-            if email is None:
-                raise ValidationError(f"Object must have user field and it should contain email")
 
             # user default user
             if email not in members_email_to_id: