Cleanup

src/models/LineItem.php

@@ -27,6 +27,7 @@
 use LitEmoji\LitEmoji;
 use yii\base\InvalidConfigException;
 use yii\behaviors\AttributeTypecastBehavior;
+use yii\validators\Validator;
 
 /**
  * Line Item model representing a line item on an order.
@@ -445,7 +446,8 @@ public function defineRules(): array
             $purchasable = Craft::$app->getElements()->getElementById($this->purchasableId);
             if ($purchasable && !empty($purchasableRules = $purchasable->getLineItemRules($this))) {
                 foreach ($purchasableRules as $rule) {
-                    $rules[] = $this->_normalizePurchasableRule($rule);
+                    $this->_normalizePurchasableRule($rule);
+                    $rules[] = $rule;
                 }
             }
         }
@@ -456,19 +458,17 @@ public function defineRules(): array
     /**
      * Normalizes a purchasable’s validation rule.
      *
-     * @param mixed $rule
-     * @return mixed
+     * @param Validator|array $rule
      */
-    private function _normalizePurchasableRule($rule)
+    private function _normalizePurchasableRule(&$rule)
     {
-        if (isset($rule[1]) && $rule[1] instanceof \Closure) {
+        if (is_array($rule) && isset($rule[1]) && $rule[1] instanceof \Closure) {
+            // Wrap the closure in another one, so InlineValidator doesn’t bind it to the model
             $method = $rule[1];
-            $rule[1] = function($attribute, $params, $validator, $current) use($method) {
+            $rule[1] = function($attribute, $params, $validator, $current) use ($method) {
                 $method($attribute, $params, $validator, $current);
             };
         }
-
-        return $rule;
     }
 
     /**