[ty] `NoReturn`/`Never` are not handled correctly

[Bobronium]

Summary

cat test.py

import os
from typing import Never, reveal_type


def fast_exit(code: int = 0) -> Never:
    os._exit(code)



try:
    foo = "bar"
except KeyboardInterrupt:
    fast_exit()

print(foo)
reveal_type(fast_exit())

ty check test.py --output-format concise

error[lint:invalid-return-type] test.py:5:33: Function can implicitly return `None`, which is not assignable to return type `Never`
warning[lint:possibly-unresolved-reference] test.py:15:7: Name `foo` used when possibly not defined
info[revealed-type] test.py:16:1: Revealed type: `Never`
Found 3 diagnostics

Adding raise statement after fast_exit() solves possibly-unresolved-reference as well as adding raise to fast_exit solves invalid-return-type:

def fast_exit(code: int = 0) -> Never:
    os._exit(code)
    raise

try:
    foo = "bar"
except KeyboardInterrupt:
    fast_exit()
    raise

Version

ty 0.0.0-alpha.5 (ff9000864 2025-05-06)