MAGETWO-28254: ConfigurableProduct Integration API

    - Fix exception when an option is deleted

Author: Yu Tang

app/code/Magento/ConfigurableProduct/Model/Resource/Product/Type/Configurable/Attribute/Collection.php

@@ -263,7 +263,12 @@ protected function _loadPrices()
             $values = $this->getPriceValues();
 
             foreach ($values as $data) {
-                $this->getItemById($data['product_super_attribute_id'])->addPrice($data);
+                $item = $this->getItemById($data['product_super_attribute_id']);
+                //the price values is cached, it could have gotten out of sync with current items
+                //when a filter is added, in that case, we just ignore the data from the cache
+                if ($item) {
+                    $item->addPrice($data);
+                }
             }
         }
         return $this;