Assert False is not cutting branches

[stolati]

Describe the Bug

When places in the code should never arrive, I do put assert False to cut the branch, but it's not taken into account after switching to pyrefly.

Sandbox Link

https://pyrefly.org/sandbox/?code=FAEwpgZgBBCWA2YD6B7ADmAdkgti8AFLAFxQDOALgE4CUUAtAHznXHBQdSzSxQC8fKAHIqQtpwlQqYCgFcqmLu07cu-QUIDuY5ZKkz5i2LqgBDMmTBUKUAGKn4lgDRQARADkUFABaxMAcxgUWUwQVygAYigAERQwMkwhG00UKgBrYEzwaDhEVAxsPEISFloGZkoqcRUedWFRar1pOQUlCVVeAWFtRslmwzbOKlNYSygANQdZMABRKipUglcKLxRXOiiU9LIoNAWMKngAT0ygA

(Only applicable for extension issues) IDE Information

No response

[yangdanny97]

Thanks for reporting! This one should be fairly easy so I'll describe the fix if anyone wants to pick it up.

The fix is probably to check if the assert condition is trivially false, and if so, mark the control flow similar to how we do for raise.

Then, we would probably want to add an integration test case to pyrefly/lib/tests/flow.rs