public void Picker(object sender, System.EventArgs e) { //this is honestly the weirdest stuff, the about view model somehow gets instantiated and called before //the actual page appears, so on app start up, and this gets run, even though the binding context hasn't been //set yet, so it crashes here on startup because _viewModel is null. Needed to add this just to stop it //from crashing at startup if (_viewModel != null) { _viewModel.UpdateDonutChart(); } }