[mac] ViewModel is allowed to be null

2 files changed, 8 insertions, 7 deletions

diff --git a/Xamarin.PropertyEditing.Mac/Controls/Custom/BrushTabViewController.cs b/Xamarin.PropertyEditing.Mac/Controls/Custom/BrushTabViewController.cs
index dd63955..dc956e3 100644
--- a/Xamarin.PropertyEditing.Mac/Controls/Custom/BrushTabViewController.cs
+++ b/Xamarin.PropertyEditing.Mac/Controls/Custom/BrushTabViewController.cs
@@ -58,7 +58,7 @@ namespace Xamarin.PropertyEditing.Mac
 			this.inhibitSelection = true;
 			base.OnViewModelChanged (oldModel);

 

-			var existing = new HashSet<CommonBrushType> (ViewModel?.BrushTypes?.Values ?? Array.Empty<CommonBrushType> ());

+			var existing = new HashSet<CommonBrushType> (oldModel?.BrushTypes?.Values ?? Array.Empty<CommonBrushType> ());

 			existing.IntersectWith (this.brushTypeTable.Keys);

 

 			var removed = new HashSet<CommonBrushType> (this.brushTypeTable.Keys);

diff --git a/Xamarin.PropertyEditing.Mac/Controls/Custom/PropertyButton.cs b/Xamarin.PropertyEditing.Mac/Controls/Custom/PropertyButton.cs
index fab17c6..9846e2c 100644
--- a/Xamarin.PropertyEditing.Mac/Controls/Custom/PropertyButton.cs
+++ b/Xamarin.PropertyEditing.Mac/Controls/Custom/PropertyButton.cs
@@ -18,14 +18,15 @@ namespace Xamarin.PropertyEditing.Mac
 		{
 			get { return viewModel; }
 			set {
-				if (viewModel != null) {
-					viewModel.PropertyChanged -= OnPropertyChanged;
+				if (this.viewModel != null) {
+					this.viewModel.PropertyChanged -= OnPropertyChanged;
 				}
 
-				viewModel = value;
-				viewModel.PropertyChanged += OnPropertyChanged;
-
-				ValueSourceChanged (viewModel.ValueSource);
+				this.viewModel = value;
+				if (this.viewModel != null) {
+					this.viewModel.PropertyChanged += OnPropertyChanged;
+					ValueSourceChanged (this.viewModel.ValueSource);
+				}
 			}
 		}