[fix] add missing properties

Author: Marcel Hauri

app/code/Magento/Widget/Model/Widget/Instance.php

@@ -96,6 +96,16 @@ class Instance extends \Magento\Framework\Model\AbstractModel
      */
     protected $_relatedCacheTypes;
 
+    /**
+     * @var \Magento\Catalog\Model\Product\Type
+     */
+    protected $_productType;
+
+    /**
+     * @var \Magento\Widget\Model\Config\Reader
+     */
+    protected $_reader;
+
     /**
      * @var \Magento\Framework\Escaper
      */