Argument 2 passed to form_input() must be of the type string, null given

Hello, can someone explain what is wrong with this?
Works fine if I just use <input statement.

Code:

public function new()
    {
        $document = new Document();

        return view('Documents/new', ['document' => $document]);
    }
    
// Form shared with edit.php and new.php
   <?= form_input(
        'title',
        old('title', esc($document->title)),
        ['class' => 'form-control'],
        'text'
    ) ?>

TypeError
Argument 2 passed to form_input() must be of the type string, null given

The old() function returned null, while the form_input() function expects a string. Actually it is written in the text of an error.
The old() function returns null if no value is found and no default value is defined. But since you defined it, it means that your default value also returns null.

By saying it works fine you mean

PHP Code:

<input value="<?=esc($document->title)?>"> 


The esc() function ignores the null value and returns as is.
The null value is always converted to an empty string

I have to define it or my edit function does not fill the field.

I solved it by doing this.

Code:

<?= form_input(
        'title',
        old('title', esc($document->title) ?? ""),
        ['class' => 'form-control'],
        'text'
    ) ?>

is this the best way?

If the Document is an instance of an Entity, then it seems to me that it would be better to define a default value.

PHP Code:

protected $attributes = ['title' => '']; 


If the Document is an instance of an Entity, then it seems to me that it would be better to define a default value.

PHP Code:

protected $attributes = ['title' => '']; 


Thank you, I like your solution better.