debug: Check if callback is actually callable

Testing if [__CLASS__, 'get_products'] is callable.
If NO, PHP cannot call the method (maybe method doesn't exist or wrong visibility).
If YES but still not called, WordPress routing issue.

includes/Api/ProductsController.php

@@ -27,9 +27,13 @@ class ProductsController {
 		error_log('WooNooW ProductsController::register_routes() START');
 		
 		// List products
+		$callback = [__CLASS__, 'get_products'];
+		$is_callable = is_callable($callback);
+		error_log('WooNooW ProductsController: Callback is_callable: ' . ($is_callable ? 'YES' : 'NO'));
+		
 		$result = register_rest_route('woonoow/v1', '/products', [
 			'methods' => 'GET',
-			'callback' => [__CLASS__, 'get_products'],
+			'callback' => $callback,
 			'permission_callback' => [Permissions::class, 'check_admin_permission'],
 		]);
 		error_log('WooNooW ProductsController: GET /products registered: ' . ($result ? 'SUCCESS' : 'FAILED'));