docs: def setup_errors(app, error_template="error.html"):
      """Add a handler for each of the available HTTP error responses."""
      def error_handler(error):
          if isinstance(error, HTTPException):
              description = error.get_description(request.environ)
              code = error.code
              name = error.name
          else:
              description = error
              code = 500
              name = "Internal Server Error"
          return render_template(error_template,
                                 error=error,
                                 code=code,
                                 name=Markup(name),
                                 description=Markup(description)), code
  
      for exception in default_exceptions:
          app.register_error_handler(exception, error_handler)