Fixed #35424 -- Checked order_with_respect_to is available when migrating _order fields.

Migrations would crash following the removal of an order_with_respect_to
field from a model and the addition of an _order field.

django/db/migrations/state.py

@@ -761,8 +761,11 @@ class ModelState:
         return self.name.lower()
 
     def get_field(self, field_name):
-        if field_name == "_order":
+        if (
-            field_name = self.options.get("order_with_respect_to", field_name)
+            field_name == "_order"
+            and self.options.get("order_with_respect_to") is not None
+        ):
+            field_name = self.options["order_with_respect_to"]
         return self.fields[field_name]
 
     @classmethod

tests/migrations/test_state.py

@@ -1131,6 +1131,22 @@ class StateTests(SimpleTestCase):
         self.assertIsNone(order_field.related_model)
         self.assertIsInstance(order_field, models.PositiveSmallIntegerField)
 
+    def test_get_order_field_after_removed_order_with_respect_to_field(self):
+        new_apps = Apps()
+
+        class HistoricalRecord(models.Model):
+            _order = models.PositiveSmallIntegerField()
+
+            class Meta:
+                app_label = "migrations"
+                apps = new_apps
+
+        model_state = ModelState.from_model(HistoricalRecord)
+        model_state.options["order_with_respect_to"] = None
+        order_field = model_state.get_field("_order")
+        self.assertIsNone(order_field.related_model)
+        self.assertIsInstance(order_field, models.PositiveSmallIntegerField)
+
     def test_manager_refer_correct_model_version(self):
         """
         #24147 - Managers refer to the correct version of a