AccountController.viewProfile 문의

@GetMapping("/profile/{nickname}")
public String viewProfile(@PathVariable String nickname, Model model, @CurrentUser Account account) {
    Account byNickname = accountRepository.findByNickname(nickname);
    if (nickname == null) {
        throw new IllegalArgumentException(nickname + "에 해당하는 사용자가 없습니다.");
    }

    model.addAttribute(byNickname);
    model.addAttribute("isOwner", byNickname.equals(account));
    return "account/profile";
}

if (nickname == null)