Bug? in generated array shape in `reference.php` at `handlers.channels.elements`

[ThomasLandauer]

I think this passage in config/reference.php is wrong:

 *         channels?: string|array{
 *             type?: scalar|null,
 *             elements?: list<scalar|null>,
 *         },

According to the last line, this should be allowed:

'channels'     => [
    'elements' => [null]
]

but I'm getting:

Monolog configuration error: The logging channel "" assigned to the "filter_for_errors" handler does not exist.

See also symfony/symfony-docs#21626 for a ~related docs PR.