Move check to the saving part of the products.

This will make it possible to use other parts of this package without having to use django 4 or postgres

oscar_odin/apps.py

@@ -18,6 +18,3 @@ def ready(self):
 
         # Register the Django model field resolver
         registration.register_field_resolver(ModelFieldResolver, Model)
-
-        # pylint: disable=W0611
-        from .checks import odin_startup_check

oscar_odin/mappings/context.py

@@ -173,12 +173,20 @@ def bulk_update_or_create_foreign_keys(self):
                 Model.objects.bulk_update(instances, fields=fields)
 
     def bulk_update_or_create_instances(self, instances):
-        instances_to_create, instances_to_update = separate_instances_to_create_and_update(
+        (
+            instances_to_create,
+            instances_to_update,
+        ) = separate_instances_to_create_and_update(
             self.Model, instances, self.identifier_mapping
         )
 
         validated_create_instances = self.validate_instances(instances_to_create)
         self.Model.objects.bulk_create(validated_create_instances)
+        for instance in validated_create_instances:
+            if instance.pk is None:
+                raise OscarOdinException(
+                    "django-oscar-odin does not support sqlite3 with Django < 4. Please use engines that have can_return_rows_from_bulk_insert set to True (like Postgres) or upgrade your Django version to 4 or higher."
+                )
 
         fields = self.get_fields_to_update(self.Model)
         if fields is not None: