A collection with cascade="all-delete-orphan" was no longer referenced by the owning entity instance:　I wanna resolve this Error

I'm currently developing the application like a making blog service. Then, I added some functions that could edit and delete the blog. In order to add the function that could delete the blog that has comment object, I wrote the code "@OneToMany(mappedBy="blog",cascade=CascadeType.ALL,orphanRemoval=true)" then, it couldn't be editing the blog. The Error occurred. Please tell me where to modify. I'm a beginner.

Java 8
spring boot version 2.2.12

A collection with cascade="all-delete-orphan" was no longer referenced by the owning entity instance: jp.kuroda.sampleBlog.model.Blog.comments; nested exception is org.hibernate.HibernateException:

at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
    at com.sun.proxy.$Proxy1467.save(Unknown Source)
    at jp.kuroda.sampleBlog.service.BlogService.editBlog(BlogService.java:54)
    at jp.kuroda.sampleBlog.controller.PersonController.editBlog(PersonController.java:100)

@Entity   
@Data  
public class Blog {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer id;  

    @ManyToOne
    private Person person;

    @OneToMany(mappedBy="blog",cascade=CascadeType.ALL,orphanRemoval=true)
    private List<Comment> comments; 
}

@Entity  
@Data  
public class Comment {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer id;

    @ManyToOne
    @JoinColumn(name="blog_id")
    private Blog blog;

    @ManyToOne
    private Person person;
}
  
@Service
public class BlogService {
    public void editBlog(Blog blog) { 
        blog.setPostDateTime(LocalDateTime.now()
             .format(DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss")));
        blogRepository.save(blog);
    }

    public void deleteBlog(Blog blog) {
        blogRepository.deleteById(blog.getId());
    }
}

@Controller
@RequestMapping("/person")
public class PersonController {
    @Autowired
    private PersonService personService;

    @Autowired
    private BlogService blogService;

    @GetMapping("/blog/{blogId}/edit")
    public String editBlog(@PathVariable("blogId")Blog blog,Model model) {
        model.addAttribute("base64image",blog.getBase64_str());
        model.addAttribute("blog",blog);
        return"person/create";
    }

    @PostMapping("/blog/{blogId}/edit")
    public String editBlog(@Valid Blog blog,BindingResult bindingResult) {
        if(bindingResult.hasErrors()) {
            return"person/create";
        }
        blogService.editBlog(blog);
        return"redirect:/person/edit";
    }
}