             case .Mapping(let dictionary) where dictionary[key] != nil:
                 return dictionary[key]!
             default:
-                return .Null
+                return .Null(NSError(domain: SwiftyJSONErrorDomain, code: 0, userInfo: nil))
             }
         }
     }

        case let string as NSString:
            self = .ScalarString(string)
        case let null as NSNull:
            self = .Null
        case let array as NSArray:
            var aJSONArray = Array<JSON>()
            for object : AnyObject in array {

            }
            self = .Mapping(aJSONDictionary)
        default:
            self = .Null(nil)
        }
    }
}
