Fixed nullref issue in MockVbeBuilder

Author: mansellan

RubberduckTests/Mocks/MockVbeBuilder.cs

@@ -180,7 +180,7 @@ private Mock<IVBE> CreateVbeMock()
             vbe.SetupProperty(m => m.ActiveCodePane);
             vbe.SetupProperty(m => m.ActiveVBProject);
 
-            vbe.SetupGet(m => m.SelectedVBComponent).Returns(() => vbe.Object.ActiveCodePane.CodeModule.Parent);
+            vbe.SetupGet(m => m.SelectedVBComponent).Returns(() => vbe.Object.ActiveCodePane?.CodeModule?.Parent);
             vbe.SetupGet(m => m.ActiveWindow).Returns(() => vbe.Object.ActiveCodePane.Window);
 
             var mainWindow = new Mock<IWindow>();