Fixed random crash when updating rows in DynamicGrids

inabox.wpf/DynamicGrid/Grids/DynamicGrid.cs

@@ -348,11 +348,11 @@ public abstract class DynamicGrid<T> : BaseDynamicGrid, IDynamicGridUIComponentP
     public void UpdateRow(CoreRow row, T obj, bool invalidateRow = true)
     {
         ObjectToRow(obj, row);
-        ObjectToRow(obj, _recordmap[row]);
+        if (_recordmap.TryGetValue(row, out var _value)) 
+            ObjectToRow(obj, _value);
         if (invalidateRow)
-        {
             InvalidateRow(row);
-        }
+        
     }
 
     public void UpdateRows(CoreRow[] rows, T[] objs, bool invalidateRows = true)