Update Additional.php

Declare module namespace before template path

Author: mageprince

app/code/Magento/Catalog/Block/Product/View/Additional.php

@@ -25,7 +25,7 @@ class Additional extends \Magento\Framework\View\Element\Template
     /**
      * @var string
      */
-    protected $_template = 'product/view/additional.phtml';
+    protected $_template = 'Magento_Catalog::product/view/additional.phtml';
 
     /**
      * @return array