fix(phpstan): code improvements and resolve warnings

Reviewed code and made several improvements which provide better error handling, code quality, and resolved warnings. The changes include:

• Syntax modifications for better readability,
• Ensured variable type checks before using methods,
• Resolved warning instances in phpstan,
• Adapted code to comply with modern PHP nullable type indicator.

Alongside, made version update in phive/phars.xml. Also, unnecessary comments or instances are removed for a cleaner code.

Related: #16 (closed)

src/QUI/ERP/Coupons/Products/PhysicalCouponProductType.php

@@ -3,6 +3,7 @@
 namespace QUI\ERP\Coupons\Products;
 
 use QUI;
+use QUI\Locale;
 
 /**
  * Class PhysicalCouponProductType
@@ -51,7 +52,7 @@ public function __construct(int $pid, array $product = [])
      * @param QUI\Locale|null $Locale
      * @return string
      */
-    public static function getTypeTitle(QUI\Locale $Locale = null): string
+    public static function getTypeTitle(null | QUI\Locale $Locale = null): string
     {
         if ($Locale === null) {
             $Locale = QUI::getLocale();
@@ -61,10 +62,10 @@ public static function getTypeTitle(QUI\Locale $Locale = null): string
     }
 
     /**
-     * @param QUI\Locale $Locale
+     * @param Locale|null $Locale
      * @return string
      */
-    public static function getTypeDescription($Locale = null): string
+    public static function getTypeDescription(null | QUI\Locale $Locale = null): string
     {
         if ($Locale === null) {
             $Locale = QUI::getLocale();