Summary of a problem or a feature request

I encountered this problem when checking this little piece of code inside a Symfony controller:

        if ($this->tokenStorage->getToken()) {
            return $this->tokenStorage->getToken()->getUser();
        }

PHPStan should infer that, since we checked the getter inside the if, we can safely exclude that the getter returns null here.

Code snippet that reproduces the problem

The code to reproduce the issue is here: https://phpstan.org/r/10c11895e307276cd46b1501d63e1cba

<?php declare(strict_types = 1);

class HelloWorld
{
	private $a;

	/**
	 * @return \DateTimeInterface|null
	 */
	public function getA() 
	{
		return $this->a;
	}
}

$class = new HelloWorld();
if ($class->getA()) {
	echo $class->getA()->format('Y-m-d');
}

Expected output

The expected output should be no errors, instead we get Cannot call method format() on DateTimeInterface|null.