Go 미들웨어 체인의 오류를 처리하는 방법은 무엇입니까?

// Pattern for a middleware function that checks for errors from the next handler.
func errorHandler(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        err := next.ServeHTTP(w, r)
        if err != nil {
            // Handle the error, e.g., by logging or returning an appropriate HTTP response.
        }
    })
}

type errorHandler func(http.ResponseWriter, *http.Request) error

// Create a special error-aware logging middleware.
func loggingWithErrorHandler(next errorHandler) errorHandler {
    return func(w http.ResponseWriter, r *http.Request) error {
        // Before executing the handler.
        start := time.Now()
        log.Printf("Started %s %s", r.Method, r.URL.Path)
        err := next(w, r)
        // After executing the handler.
        log.Printf("Completed %s in %v", r.URL.Path, time.Since(start))
        return err
    }
}

// Define an error-returning handler func.
func errorHandlerFunc(w http.ResponseWriter, r *http.Request) error {
    w.Write([]byte("Hello World from errorHandlerFunc!"))
    return nil
}

// Assemble the middleware chain and error-aware middleware.
http.Handle("/", loggingWithErrorHandler(errorHandlerFunc))