[TSP] codeaction error

[kinto0]

Environment data

• Pylance trunk
• Pyrefly 0.63.1
• Type server set to Pyrefly

Repro Steps

• unknown

## Environment data

- Pylance trunk
- Pyrefly 0.63.1
- Type server set to Pyrefly

## Code snippet

class Foo: ...
class Base(Foo): ...

## Repro Steps
- type hierarchy request on `Base`
- type hierararchy does not work (empty response)
- notice error message (maybe unrelated?)

2026-04-29 10:44:05.963 [trace] Received response 'typeHierarchy/subtypes - (1242)' in 5ms. Request failed: Request typeHierarchy/subtypes failed with message: Cannot read properties of undefined (reading 'decoratorDataClassBehaviors') (-32603).
2026-04-29 10:44:05.963 [error] Request typeHierarchy/subtypes failed.
Message: Request typeHierarchy/subtypes failed with message: Cannot read properties of undefined (reading 'decoratorDataClassBehaviors')
Code: -32603

[gramster]

Type hierarchy works the opposite way. If you click on Foo and ask for the type hierarchy you will get a tree showing the classes that derive from Foo.

[gramster]

I think this is just user error; the code action shows subtypes, not base types.