Global Error Handling in ASP.NET Core API 3

http://www.asp.net/web-api/overview/error-handling/web-api-global-error-handling 

 [HttpPost]
        public async Task<IActionResult> Post(Starship starship)
        {
            try
            {
                if (starship.Classification == "Defense" && 
                    string.IsNullOrEmpty(starship.Description))
                {
                    ModelState.AddModelError(nameof(starship.Description),
                        "For a 'Defense' ship " +
                        "classification, 'Description' is required.");
                }
                else
                {
                    // Process the form asynchronously
                    // async ...

                    return Ok(ModelState);
                }
            }
            catch (Exception ex)
            {
                logger.LogError("Validation Error: {MESSAGE}", ex.Message);
            }

            return BadRequest(ModelState);
        }