class GraphQL::StaticValidation::FieldsAreDefinedOnTypeError

def code 

def code
  "undefinedField"
end

def initialize(message, path: nil, nodes: [], type:, field:) 

def initialize(message, path: nil, nodes: [], type:, field:)
  super(message, path: path, nodes: nodes)
  @type_name = type
  @field_name = field
end

def to_h

A hash representation of this Message 
def to_h
  extensions = {
    "code" => code,
    "typeName" => type_name,
    "fieldName" => field_name
  }
  super.merge({
    "extensions" => extensions
  })
end