🤖 Fix event products endpoint 500 response (TypeError)

[Leonard013]

🤖 Fix Event Products endpoint 500 response

Description

This pull request resolves a 500 internal server error on the /api/events/{event_id}/products route.

Root Cause

In GetProductsHandler::handle, $productPaginator->getCollection() returns a collection of ProductDomainObjects. However, this collection was passed directly to $this->productFilterService->filter(...).

The ProductFilterService::filter method expects a collection of ProductCategoryDomainObjects and processes it by calling $category->getProducts() inside a flatMap closure. Since ProductDomainObject does not implement getProducts(), this mismatch triggers a PHP strict typing TypeError (or an Error for undefined method depending on configuration).

Fix

1. Isolated the product-specific filtering logic inside ProductFilterService into a new public method filterProducts(Collection $products, ...): Collection.
2. Refactored ProductFilterService::filter to call filterProducts internally to avoid code duplication and preserve existing functionality for category-based filtering.
3. Updated GetProductsHandler to invoke the new filterProducts method on the retrieved ProductDomainObject collection.
4. Added unit test suite under backend/tests/Unit/Services/Application/Handlers/Product/GetProductsHandlerTest.php that verifies:
   • Handler integration behaves as expected.
   • The type mismatch correctly throws a TypeError in filter under the original implementation parameters.

All backend unit tests pass successfully.

Closes #1268 🤖

[Leonard013]

I have read the CLA Document and I hereby sign the CLA

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}