sys.exit is not being acknowledged as an exit point of the function #454

Summary

I don't know how to describe it exactly, but running ty check on the following code shows an invalid-return-type because the code does not acknowledges that sys.exit is equivalent o a raise SystemExit and thus the function will not return anything.

def config(thing) -> dict:
    if thing:
        return {'response': thing}
    sys.exit(-1)

This is a dumbed down version of a real function on a real codebase, where the code exits if some config is not passed correctly. In all successful function calls, it will return a dict otherwise it will raise SystemExit. There is no possible "None" being returned as suggested:

error[invalid-return-type]: Function can implicitly return `None`, which is not assignable to 
return type `dict[Unknown, Unknown]`
 --> foo.py:4:17
  |
4 | def config(thing) -> dict:
  |                      ^^^^
5 |     if thing:
6 |         return {'response': thing}
  |

Version

ty 0.0.1-alpha.5 (3b726d8 2025-05-17)