fixed: get traces

src/Hotline.Api/Controllers/WorkflowController.cs

@@ -458,8 +458,7 @@ public class WorkflowController : BaseController
             .OrderBy(d => d.CreationTime)
             .ToTreeAsync(d => d.Traces, d => d.ParentId, null);
 
-        var a = _mapper.Map<WorkflowDto>(workflow);
-        return a;
+        return _mapper.Map<WorkflowDto>(workflow);
     }
 
     /// <summary>