Description:
------------
Since upgrading to PHP 7.4, I get the following PHP Warning:
Declaration of Go\ParserReflection\ReflectionMethod::getClosure($object) should be compatible with ReflectionMethod::getClosure($object = NULL)

The above framework class is extending ReflectionMethod and until 7.3.x the declaration of ReflectionMethod::getClosure($object) apparently didn't have default null value, now making it incompatible with the subclass declaration.

The change is not reflected in the release notes of PHP 7.4.0 or in the current documentation:
https://www.php.net/manual/en/reflectionmethod.getclosure.php

Test script:
---------------
<?php

class ReflectionMethodSubclass extends ReflectionMethod {
    public function getClosure($object) {
        return parent::getClosure($object);
    }
}