def error
            error = (self[:error_upgrade] & 0b1111111)
            return nil if error == 0

            err = ::HttpParser.err_name(error)[4..-1] # HPE_ is at the start of all these errors
            klass = ERRORS[err.to_sym]
            err = "#{::HttpParser.err_desc(error)} (#{err})"
            return klass.nil? ? Error::UNKNOWN.new(err) : klass.new(err)
        end
def error
            error = (self[:error_upgrade] & 0b1111111)
            return nil if error == 0

            err = ::HttpParser.err_name(error)[4..-1] # HPE_ is at the start of all these errors
            klass = ERRORS[err.to_sym]
            err = "#{::HttpParser.err_desc(error)} (#{err})"
            return klass.nil? ? Error::UNKNOWN.new(err) : klass.new(err)
        end
Returns the error that occurred during processing.

 @return [StandarError]
   Returns the error that occurred.