Description:
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Segfault while access a non-string property of DateInterval object

Test script:
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<?php
class Crasher extends DateInterval {
    public function __construct($time_spec) {
        parent::__construct($time_spec);
        var_dump($this->{2});
    }   
}   
$c = new Crasher("P2Y4DT6H8M");

Expected result:
----------------
NULL

Actual result:
--------------
core dump