ENGCOM-4350: Query Cart returns internal server error if configurable product was added #383

 - Merge Pull Request magento/graphql-ce#383 from XxXgeoXxX/graphql-ce:2.3-develop#380
 - Merged commits:
   1. cfbbe0d

Author: magento-engcom-team

app/code/Magento/QuoteGraphQl/etc/di.xml

@@ -12,6 +12,7 @@
             <argument name="supportedTypes" xsi:type="array">
                 <item name="simple" xsi:type="string">SimpleCartItem</item>
                 <item name="virtual" xsi:type="string">VirtualCartItem</item>
+                <item name="configurable" xsi:type="string">ConfigurableCartItem</item>
             </argument>
         </arguments>
     </type>