Crash when validating `QuerySet.order_by()`

# Bug report I'm testing out the master branch on a very large repo at work to check that everything is working before we make a release as there are a significant number of changes. ## What's wrong It looks like we have a crash in the new validation for `Queryset.order_by()`. I've not managed to create a minimal reproducer yet, but here's the traceback: ```pytb Please report a bug at https://github.com/python/mypy/issues version: 1.19.1 Traceback (most recent call last): File "<frozen runpy>", line 198, in _run_module_as_main File "<frozen runpy>", line 88, in _run_code File "mypy/checkexpr.py", line 6103, in accept File "mypy/checkexpr.py", line 6138, in accept_maybe_cache File "mypy/nodes.py", line 2289, in accept File "mypy/checkexpr.py", line 508, in visit_call_expr File "mypy/checkexpr.py", line 645, in visit_call_expr_inner File "mypy/checkexpr.py", line 1496, in check_call_expr_with_callee_type File "mypy/checkexpr.py", line 1589, in check_call File "mypy/checkexpr.py", line 1832, in check_callable_call File "mypy/checkexpr.py", line 1287, in apply_function_plugin File ".../.venv/lib/python3.13/site-packages/mypy_django_plugin/transformers/querysets.py", line 930, in validate_order_by _validate_order_by_lookup(ctx, django_model.cls, parts) ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File ".../.venv/lib/python3.13/site-packages/mypy_django_plugin/transformers/querysets.py", line 915, in _validate_order_by_lookup Query(model_cls).names_to_path(parts, model_cls._meta, fail_on_missing=True) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File ".../.venv/lib/python3.13/site-packages/django/db/models/sql/query.py", line 1789, in names_to_path name = opts.pk.name ^^^^^^^^^^^^ AttributeError: 'NoneType' object has no attribute 'name' ``` ## System information - OS: - `python` version: 3.13 - `django` version: 6.0.3 - `mypy` version: 1.19.1 - `django-stubs` version: master - `django-stubs-ext` version: master