Merge pull request #4 from korobkovandrey/fix/field-resolve-error

fix/field-resolve-error: fix error exception for non BackedEnum when n…

Author: trippo

src/Enum.php

@@ -19,7 +19,10 @@ public function __construct($name, $attribute = null, callable $resolveCallback
         parent::__construct($name, $attribute, $resolveCallback);
         $this->resolveUsing(
             function ($value) {
-                return $value instanceof UnitEnum ? $value->value : $value;
+                if($value instanceof BackedEnum){
+                    return $value->value;
+                }
+                return $value instanceof UnitEnum ? $value->name : $value;
             }
         );