Need some help with my end-point

c++
{
    [Route("[controller]")]
    [ApiController]
    public class StepController : ControllerBase
    {
        private readonly DataContext _context;

        public StepController(DataContext context)
        {
            _context = context;
        }


        [HttpGet]
        public async Task<ActionResult<List<Step>>> Get(string databaseName, int workflowKey)
        {
            string query = "SQLQUERY";

            // some of the data is indeed NULL, my guess would be that calling the below function on that data gives the error?
            var steps = await _context.steps.FromSqlRaw(query).ToListAsync();

            return Ok(steps);

        }
    }

c++
    public class Step
    {
        [Key]
        public int Key { get; set; }
        public string Type { get; set; }
        public int ParentKey { get; set; }
        public string SubWorkflowCode { get; set; }
        public int Sequence { get; set; }
        public int WorkflowKey { get; set; }
        [NotMapped]
        public List<Parameters> Parameters { get; set; }
    }

    public class Parameters
    {
        public string Name { get; set; }
        public string Source { get; set; }
        public string Value { get; set; }
    }

c++
var steps = await _context.steps.FromSqlRaw(query).ToListAsync();

System.Data.SqlTypes.SqlNullValueException: Data is Null. This method or property cannot be called on Null values.