Narrowing inside `try` is preserved into `finally`, ignoring type outside of `try`

[yangdanny97]

Describe the Bug

from typing import *


def something_that_might_throw() -> None:
    raise Exception()
        
class Thing():
    def something(self) -> None:
        pass

def blah() -> None:
    x = None
    try:
        something_that_might_throw()
        if x is None:
            x = Thing()
    except Exception:
        raise
    finally:
        reveal_type(x) # revealed type: Thing, but it could be `None`
        x.something()

Python: 3.12

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeS4ATrgLYAEALqcROgOZ0Q3G6UN0AqADroRIzDDB04tGAwAWrNgH0FqBspoQ28jQuoB3ABQBKOgFoAfHQByudDEQi6LupVQQ4MOgFF8AYxhiBgh7U2dXSJF-KFQ4ODoAFUV2Uyd0SIkpGRo5FLYjLygwMytbe0cIyJdiOLgxLEk6bFj5UwtrOwd0yPw6AF5yhyrGSlIe6pccvKVVeXVNbV05w3CMyc4pPs8hyvWN1z7B5KU1yJgAoP4-QODQ9AnJ908YEch0VCgocZHIyhgAG4wT6qZgwIz4MwAYjcgOBsEwjDBiCS%2BQANM0AK78CD8fy4TFQRHYbwAAy6MFJv0OhGmClOJhAaJAZH%2BYG%2BhAYtCgFBhAAVSGzvtIMDgCHR8ehIGxMe4QvZCCIYQBlGDeXQMYhwRAAeh1rMkHN4bB1MHQOswuH8cB1kulsvU9x1dDAvDoqABHliLW8du0DvlGVwd3scEV6DICns5iBlDg9wGdCEIAAzIQAIwAJmTIgA2jBKNQ4wBdESY9BcHh8GCYcyYCD-fwhIGJgDk2nQvBgrZEnYY5n%2BAEdMQ2a%2BYANYwUjmVD%2BQLxNsGVCUdA99AgAC%2BzNnzZgADFoDAKGgsHgiGRN0A

(Only applicable for extension issues) IDE Information

I'm not sure what the desired behavior is, but clearly we're guessing wrong in this case by taking the refined type from the try.

If we take the original type before the try then it doesn't account for the fact that the try could have succeeded. I thought we created a flow branch at the beginning of the try-block and merging the two branches should have handled this, but something is going wrong.