Describe the Bug

Minimal repro:

def test() -> int:
    return

Expected: Return type mismatch None vs. int
Actual: No error

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeSImMYABGLrgBQCUNAtAHw0ToAuiAHXQ0RNAE4xeAVzHoQAGhBTe0OCXKIQAYhoBVFVAi9SdKegDGK3OjhChVWvTEBbVLwD66Kc%2BwwxjfERuPlZOGjheMUFhUQlpWToBEAA5b18ommB8AF8koQUQMgkwKFJCXlxnKAodAAVSYtLwjBwCGnNrSABzGTcIa0IhHQBlGBgaAAteXmI4RAB6eaLqUsJcMS75mHR5zFxzOHmO9G7eqx26dZpUADdUaFRsWHbOiB6xPusaXGJztSEyLwJtY2Dc-HB%2BsIALw0JIAZkIAEYAEx5OTZRSoSwQMEAMWgMAoaCweCIZBA2SAA

(Only applicable for extension issues) IDE Information

No response