Pie: Refresh() throws argument exception when called from inside a WPF initializer

The following is the three lines of code:

```cs
double[] values = { 778, 283, 184, 76, 43 };
WpfPlot1.Plot.AddPie(values);
WpfPlot1.Refresh();
```

When `WpfPlot1.Refresh()` is called is when the program throw the exception.

I am using version 4.1.60