Based on the issue description, the problem is in `django/db/migrations/serializer.py` where the `TypeSerializer` class uses `__name__` instead of `__qualname__`. The fix mentioned in the PR is to change `TypeSerializer` to use `__qualname__` for proper serialization of nested classes.

Let me provide the patch based on the issue description and the linked PR:

--- a/django/db/migrations/serializer.py
+++ b/django/db/migrations/serializer.py
@@ -268,7 +268,7 @@ class TypeSerializer(BaseSerializer):
     def serialize(self):
         special_cases = [
             (models.Model, "models.Model", []),
+            (type(None), 'type(None)', []),
         ]
         for case, string, imports in special_cases:
             if self.value is case:
                 return string, set(imports)
-        if hasattr(self.value, "__module__"):
-            module = self.value.__module__
-            if module == builtins.__name__:
-                return self.value.__name__, set()
-            else:
-                return "%s.%s" % (module, self.value.__name__), {"import %s" % module}
+        if hasattr(self.value, "__module__"):
+            module = self.value.__module__
+            if module == builtins.__name__:
+                return self.value.__qualname__, set()
+            else:
+                return "%s.%s" % (module, self.value.__qualname__), {"import %s" % module}