(pyrefly maintainer here) If you haven't already, please file an issue for that crash on the [Pyrefly repo](https://github.com/facebook/pyrefly) as well :)

Pyrefly (a new language server and type checker for Python) now includes built-in support for Pydantic, a popular Python library for data validation and parsing. Previously, the only type checker that supported Pydantic was Mypy, via a plugin.

Pyrefly actually does have (experimental) support for Pydantic! https://pyrefly.org/en/docs/pydantic/

Nice, did not know.