Generic type inference incorrectly handled in edge case

Bug Report

If you try to widdle down the type of a generic class in a certain manner, it only works if you use an intermediate variable. A little tough to explain without looking at the example

To Reproduce

https://mypy-play.net/?mypy=latest&python=3.10&gist=d3ebef88a57147cef8a8d311e1b33fb7

from abc import ABC, abstractmethod
from typing import Generic, TypeVar

T = TypeVar("T")

class A(ABC, Generic[T]):

    @abstractmethod
    def t(self) -> T:
        pass

def get_a_does_work(a: A[T]) -> T:
    t_value = a.t()
    if t_value is None:
        return None 
    return a.t()

def get_a_should_work(a: A[T]) -> T:
    if a.t() is None:
        return None 
    return a.t()

Expected Behavior

Both get_a_does_work and get_a_should_work should pass type checking.

Actual Behavior

get_a_should_work outouts:
main.py:20: error: Incompatible return value type (got "None", expected "T")

Your Environment

You can see on the playground

Reproduce the behavior in the linked mypy playground using the get_a_does_work and get_a_should_work examples. Start by tracing generic type inference and narrowing for repeated a.t() calls; done when both functions pass type checking without an intermediate variable.