mypy reports no issues on access of conditionally available fields

Bug Report

To Reproduce

# foo.py
def print_foo():
    print(foo)

if __name__ == '__main__':
    foo = "foobar"

https://mypy-play.net/?mypy=latest&python=3.12&gist=d8a24e474f61a151f549728e14173383

Expected Behavior

mypy should report an error

the name foo is not guaranteed to be part of the scope in print_foo. E.g. the following code will break

import foo
foo.print_foo()

Actual Behavior

mypy outputs "Success: no issues found in 1 source file"

Your Environment

see playground link

• Mypy version used: 1.15
• Mypy command-line flags: none (but happens with --strict also)
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.11, 3.12, 3.13

Start with the minimal foo.py reproduction and run it through the linked mypy playground across the reported Python versions. Trace how mypy handles the conditionally defined global accessed by print_foo; done means it reports an error for the example while preserving valid scope analysis.