Lazy|Type properties incorrectly marked as optional in TypeScript (typescript-transformer)

[mez-coretek]

✏️ Describe the bug
When using Lazy|Type in property type hints with Lazy::closure(), the TypeScript transformer incorrectly marks properties as optional. However, using ClosureLazy|Type works correctly and keeps properties required.

The root cause is in DataTypeScriptTransformer.php line 78, which uses exact string comparison (!==) instead of inheritance checking:

|| ($dataProperty->type->lazyType && $dataProperty->type->lazyType !== ClosureLazy::class)

When you write Lazy|Type, the DataTypeFactory captures Lazy::class. Since "Lazy" !== "ClosureLazy", the property is marked as optional in TypeScript.

↪️ To Reproduce

use Spatie\LaravelData\Data;
use Spatie\LaravelData\Lazy;
use Spatie\LaravelData\Support\Lazy\ClosureLazy;

it('marks Lazy union properties as optional in TypeScript incorrectly', function () {
    class MemberData extends Data
    {
        public function __construct(
            public string $name,
            public string $email,
        ) {}
    }

    // Using abstract Lazy class in type hint
    class ShowDataWithLazy extends Data
    {
        public function __construct(
            public Lazy|MemberData $member,
        ) {}
    }

    // Using concrete ClosureLazy class in type hint
    class ShowDataWithClosureLazy extends Data
    {
        public function __construct(
            public ClosureLazy|MemberData $member,
        ) {}
    }

    // Both use Lazy::closure() at runtime
    $dataWithLazy = ShowDataWithLazy::from([
        'member' => Lazy::closure(fn () => MemberData::from(['name' => 'John', 'email' => 'john@example.com'])),
    ]);

    $dataWithClosureLazy = ShowDataWithClosureLazy::from([
        'member' => Lazy::closure(fn () => MemberData::from(['name' => 'John', 'email' => 'john@example.com'])),
    ]);

    // Generate TypeScript for both
    $transformer = app(\Spatie\LaravelData\Support\TypeScriptTransformer\DataTypeScriptTransformer::class);
    
    // ShowDataWithLazy will have member?: MemberData (optional)
    // ShowDataWithClosureLazy will have member: MemberData (required)
    
    dd([
        'with_Lazy_generates_optional' => 'member?: MemberData',
        'with_ClosureLazy_generates_required' => 'member: MemberData',
    ]);
});

Generated TypeScript output:

With Lazy|Type:

export type ShowDataWithLazy = {
    member?: MemberData;  // ❌ Optional when it shouldn't be
};

With ClosureLazy|Type:

export type ShowDataWithClosureLazy = {
    member: MemberData;  // ✅ Required as expected
};

✅ Expected behavior
Properties using Lazy::closure() should NOT be marked as optional in TypeScript, regardless of whether the type hint is Lazy|Type or ClosureLazy|Type, since ClosureLazy is specifically excluded from the optional check.

Both classes should generate the same required TypeScript property:

member: MemberData;  // Required, not optional

Suggested fix:
Change the check in DataTypeScriptTransformer.php line 78 from:

|| ($dataProperty->type->lazyType && $dataProperty->type->lazyType !== ClosureLazy::class)

To:

|| ($dataProperty->type->lazyType && !is_a($dataProperty->type->lazyType, ClosureLazy::class, true))

This would properly check if lazyType is ClosureLazy or a subclass, rather than requiring exact equality.

🖥️ Versions

Laravel: 12.x
Laravel Data: 4.15.1 (also affects 4.18.0)
PHP: 8.3.23