Example of inconsistent error code

OrderController.cs

[HttpPatch]
public async Task<IActionResult> Update([FromBody] OrderDto order)
{
    try
    {
        if (!ModelState.IsValid)
        {
            // Returns response of type `ModelState` on "Bad Request"
            return BadRequest(ModelState);
        }

        if (DoSomeCustomValidation(order))
        {
            // Returns pain-text on "Bad Request"
            return BadRequest("Order is invalid");
        }

        if (!await _repository.OrderExists(order.Id))
        {
            // Returns pain-text on "Not Found"
            return NotFound("Order is not found");
        }

        await _repository.UpdateOrder(order);
        return NoContent();
    }
    catch (Exception e)
    {
         // Only returns status code 500 on unhandled error with empty response
        return new StatusCodeResult(StatusCodes.Status500InternalServerError);
    }
}