Revert exception

Author: Alex Taranovskyi

lib/internal/Magento/Framework/GraphQl/Query/EnumLookup.php

@@ -7,9 +7,11 @@
 
 namespace Magento\Framework\GraphQl\Query;
 
+use Magento\Framework\Exception\RuntimeException;
 use Magento\Framework\GraphQl\Config\Element\Enum;
 use Magento\Framework\GraphQl\ConfigInterface;
 use Magento\Framework\GraphQl\Schema\Type\Enum\DataMapperInterface;
+use Magento\Framework\Phrase;
 
 /**
  * Processor that looks up definition data of an enum to lookup and convert data as it's specified in the schema.
@@ -27,8 +29,6 @@ class EnumLookup
     private $enumDataMapper;
 
     /**
-     * EnumLookup constructor.
-     *
      * @param ConfigInterface $typeConfig
      * @param DataMapperInterface $enumDataMapper
      */
@@ -44,11 +44,19 @@ public function __construct(ConfigInterface $typeConfig, DataMapperInterface $en
      * @param string $enumName
      * @param string $fieldValue
      * @return string
+     * @throws RuntimeException
      */
     public function getEnumValueFromField(string $enumName, string $fieldValue) : string
     {
         /** @var Enum $enumObject */
         $enumObject = $this->typeConfig->getConfigElement($enumName);
+
+        if (!($enumObject instanceof Enum)) {
+            throw new RuntimeException(
+                new Phrase('Enum type "%1" not defined', [$enumName])
+            );
+        }
+
         $mappedValues = $this->enumDataMapper->getMappedEnums($enumName);
 
         foreach ($enumObject->getValues() as $enumItem) {