fix: NullableTransformer should check if array key exists

[nikophil]

when mapping from array to an object, if a property is nullable and is not present in the original object, there should be no error if the property defaults to null.

currently, this code:

readonly class SomeClass
{
    public function __construct(public int|null $foo = null)
    {
    }
}

$autoMapper->map([], SomeClass::class);

generates the following code:

// ...

            } else {
                $value_1 = null;
                if (isset($value['foo'])) {
                    $value_1 = $value['foo'];
                }
                $constructarg = $value_1;
            }

// ...

and results in an error where foo key does not exist, although we provided a default error.

At first, I wanted to add an isset() only if the property has a default value, but it appears that it is a little bit complex: NullableTransformerFactory would need to access to property info to get the write info of the property... I think this would be overkill for the case where the property is nullable and adding a isset() everywhere we have a array access is enough and not harmful.

[Korbeil]

I fear it can break some user behavior but since there was no issues with current tests, let's merge this 👍

Thanks for the contribution @nikophil !

[nikophil]

I fear it can break some user behavior but since there was no issues with current tests, let's merge this 👍

I don't think so:

• property is not nullable: this PR is not involved
• property is nullable, and key is provided: no problem as it used to be
• property is nullable but input is not an array: this PR is not involved

If property key is missing in the input array:

• property is nullable and has default null: this is the specific use case I wanted to fix, the property will be set to null
• property is nullable and has default to something else than null: the property will be set to null (see Default values in target are not handled #8)
• property is nullable and has no default: in this case, it used to create an error, but now the property is defaulted to null. But I don't think how this could be a problem