docs: def add_log_error(self, x, flag_also_show=False, E=None):
          """Sets text of labelError."""
          if len(x) == 0:
              x = "(empty error)"
              tb.print_stack()
          x_ = x
          if E is not None:
              a99.get_python_logger().exception(x_)
          else:
              a99.get_python_logger().info("ERROR: {}".format(x_))
  
          x = '<span style="color: {0!s}">{1!s}</span>'.format(a99.COLOR_ERROR, x)
          self._add_log_no_logger(x, False)
          if flag_also_show:
              a99.show_error(x_)