exists() returns false if value is set to null

[robbiejackson]

While preparing some documentation for Joomla I noticed the following behaviour:

use Joomla\Registry\Registry;
...
$registry = new Registry();
$registry->set("x", null);
$exists = $registry->exists("x");  // returns false

I was rather surprised by this and just wanted to check if this was deliberate.

[HLeithner]

it might be unexpected but it's consistent with with isset($array['x']); when the x is null which would work if you do use array_key_exists so yes it's expected.

relevant code is:

            if (!isset($node->$n)) {
                return false;
            }

but maybe that's not expected and should be changed