Generic bad request error.
Missing required user information in the request.
Invalid email format or missing email field.
Invalid or missing product details.
Invalid or missing post data.
Invalid or missing comment data.
Invalid or missing category information.
Invalid or missing file in the request.
Invalid or missing image data.
Invalid or missing address information.
Types representing different "Bad Request" error scenarios (HTTP 400).
These error types help identify the specific reason why the request was malformed or invalid.