Cannot return null for non-nullable field AvailableShippingMethod.method_code when no shipping methods are available

Author: XxXgeoXxX

app/code/Magento/QuoteGraphQl/Model/Resolver/ShippingAddress/AvailableShippingMethods.php

@@ -10,6 +10,7 @@
 use Magento\Framework\Api\ExtensibleDataObjectConverter;
 use Magento\Framework\Exception\LocalizedException;
 use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Exception\GraphQlNoSuchEntityException;
 use Magento\Framework\GraphQl\Query\ResolverInterface;
 use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
 use Magento\Quote\Api\Data\ShippingMethodInterface;
@@ -65,13 +66,19 @@ public function resolve(Field $field, $context, ResolveInfo $info, array $value
         $shippingRates = $address->getGroupedAllShippingRates();
         foreach ($shippingRates as $carrierRates) {
             foreach ($carrierRates as $rate) {
-                $methods[] = $this->dataObjectConverter->toFlatArray(
+                $method = $this->dataObjectConverter->toFlatArray(
                     $this->shippingMethodConverter->modelToDataObject($rate, $cart->getQuoteCurrencyCode()),
                     [],
                     ShippingMethodInterface::class
                 );
+                if ($method['available'] && $method['error_message'] === "") {
+                    $methods[] = $method;
+                }
             }
         }
+        if (count($methods) === 0) {
+            throw new GraphQlNoSuchEntityException(__(' This shipping method is not available. To use this shipping method, please contact us.'));
+        }
         return $methods;
     }
 }