如何在Golang中实现多层错误传递

func readConfig() error {
    file, err := os.Open("config.json")
    if err != nil {
        return fmt.Errorf("failed to open config file: %w", err)
    }
    defer file.Close()

    _, err = parseConfig(file)
    if err != nil {
        return fmt.Errorf("failed to parse config: %w", err)
    }
    return nil
}

func loadAppConfig() error {
    err := readConfig()
    if err != nil {
        return fmt.Errorf("failed to load app config: %w", err)
    }
    return nil
}

err := loadAppConfig()
if err != nil {
    if errors.Is(err, os.ErrNotExist) {
        log.Fatal("config file not found")
    } else if pe := new(json.SyntaxError); errors.As(err, &pe) {
        log.Fatalf("invalid JSON syntax: %v", pe)
    } else {
        log.Fatalf("unexpected error: %v", err)
    }
}

type AppError struct {
    Msg string
    Err error
}

func (e *AppError) Error() string {
    return e.Msg + ": " + e.Err.Error()
}

func (e *AppError) Unwrap() error {
    return e.Err
}

if err != nil {
    return &AppError{Msg: "database query failed", Err: err}
}