Fix error when trying to create a page without extras

[tabacitu]

WHY

BEFORE - What was wrong? What was happening before this PR?

I installed PageManager and tried to create a simple "terms and conditions" page using this template:

    private function document(): void
    {
        $this->crud->addField([
            'name' => 'content',
            'label' => trans('backpack::pagemanager.content'),
            'type' => 'summernote',
            'placeholder' => trans('backpack::pagemanager.content_placeholder'),
        ]);
    }

But I couldn't do that. As soon as I hit "save" in the create form, I was hit with a big fat DB error saying that the extras column doesn't have a default.

AFTER - What is happening after this PR?

It looks like we have two migrations for this package. The first one creates the table, the second one changes the length of the extras column. But when it does that... it no longer has nullable on it, so that's forgotten.

So I've just added nullable to it - and now it works.

HOW

How did you achieve that, in technical terms?

Added nullable in the second migration file.

Is it a breaking change or non-breaking change?

Non-breaking imho but @pxpm please think about it too.

How can we test the before & after?

Try to do the same thing I explained above, in a new project. You should get an error too.

[pxpm]

This was due to recent Laravel v11 changes. When you alter a migration, you need to "re-set" the modifiers. https://laravel.com/docs/11.x/migrations#modifying-columns