The code runs great and didn't needed lot of changes. Therefore i have tried my best to improve the performance and error handling of the code.

- Removed "comments" field as not needed anymore
- Added @notblank and @NotNull annotations to ensure that title, content, and user are always provided.
- Added fetch = FetchType.LAZY to the User relationship to improve performance by loading user data only when needed.

- Added a method findByTag to retrieve posts by tag directly from the database (Improve Memory efficiency)
The method helps further in PostService.java code.

- Using findByTag method directly in getPostsByTag to improve efficiency.
- Added a custom exception (RuntimeException) to handle cases where a post is not found.
- Added @transactional annotation to updatePost and deletePost methods to ensure proper data management.