def restored_front_matter
      front_matter.map do |key, value|
        value = "null" if value.nil?
        [key, value]
      end.to_h
    end
def restored_front_matter
      front_matter.map do |key, value|
        value = "null" if value.nil?
        [key, value]
      end.to_h
    end
verbose 'null' values in front matter