MAGETWO-94207: Cart GET for customer in REST returns 400 when cart not created

Author: paliarush

app/code/Magento/Quote/Model/Webapi/ParamOverriderCartId.php

@@ -56,7 +56,7 @@ public function getOverriddenValue()
                 }
             }
         } catch (NoSuchEntityException $e) {
-            /* do nothing and just return null */
+            throw new NoSuchEntityException(__('Current customer does not have an active cart.'));
         }
         return null;
     }

lib/internal/Magento/Framework/Webapi/Rest/Request/ParamOverriderInterface.php

@@ -34,6 +34,7 @@ interface ParamOverriderInterface
      * Returns the overridden value to use.
      *
      * @return string|int|null
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
      */
     public function getOverriddenValue();
 }