code: public function getMiddleware($name) : Middleware
      {
          if (!array_key_exists($name, $this->namedMiddleware)) {
              throw new \UnexpectedValueException("No middleware registered under name '{$name}'");
          }
          return $this->namedMiddleware[$name];
      }
docs: Retrieve a middleware by name.
  
  @param string $name Name of middleware set by ->registerMiddleware($name)
  @throws UnexpectedValueException For unrecognised names
  @return Middleware The referenced middleware instance