Field's setDefault not called if value is an array (like in Map field)

[alexoleynik0]

• Laravel Version: 9.50.2
• PHP Version: 8.0.2
• Laravel-admin: 1.8.19

Description:

There's an issue with Encore\Admin\Form\Field->value method.

Because it checks only for $this->value to not be equal to null (using null coalescing operator -- return $this->value ?? $this->getDefault();).
Hence it does not get to the getDefault method if $this->value is something else from null.

For example Encore\Admin\Form\Field\Map field has value set to an array with empty values:

protected $value = [
    'lat' => null,
    'lng' => null,
];

Not sure whether it should be fixed explicitly for Map field or for Field alltogether.

Described it some more in this comment -- there're some workarounds also.

Steps To Reproduce:

1. Create Form with Map field -- $form->map('lat', 'lng', __('Location'));.
2. Set default value using default method

$form->map('lat', 'lng', __('Location'))->default(['lat' => 50.454476779599574, 'lng' => 30.517363595654306]);

3. See that it doesn't work for Creation nor for Editing of the Entity.