CreateAtRoute生成500错误

[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    private readonly IProductRepository _repository;

    public ProductsController(IProductRepository repository)
    {
        _repository = repository;
    }

    [HttpPost]
    public async Task<IActionResult> CreateProduct([FromBody] Product product)
    {
        if (ModelState.IsValid)
        {
            var createdProduct = await _repository.AddProductAsync(product);
            return CreatedAtRoute(nameof(GetProductById), new { id = createdProduct.Id }, createdProduct);
        }
        else
        {
            return BadRequest(ModelState);
        }
    }

    [HttpGet("{id}")]
    public async Task<IActionResult> GetProductById(int id)
    {
        var product = await _repository.GetProductByIdAsync(id);
        if (product == null)
        {
            return NotFound();
        }
        return Ok(product);
    }
}