e.php
<?php

class A {
private $a;
public function construct($a) {
$this->a = $a;
}
}
class B extends A {
public $a;
public function construct($privA, $a) {
parent::__construct($privA);
$this->a = $a;
}

$chain = new A(new B(new A(1), 2));
echo 1; // breakpoint here

---- end of file ----

Now if we try to run this script until the breakpoint and call property_get -d 0 -c 0 -n $chain->a->*A*a->a we will get an error instead of 1.