Add fix for multiple null refs caused by a control scheme being deleted by Undoing the creation of it via ctrl+z.

Author: Darren-Kelly-Unity

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/Commands/ControlSchemeCommands.cs

@@ -145,10 +145,16 @@ public static Command ResetSelectedControlScheme()
         {
             return (in InputActionsEditorState state) =>
             {
-                var controlSchemeSerializedProperty = state.selectedControlSchemeIndex == -1 ? null :
-                    state.serializedObject
-                        .FindProperty(nameof(InputActionAsset.m_ControlSchemes))
-                        .GetArrayElementAtIndex(state.selectedControlSchemeIndex);
+                SerializedProperty controlSchemeSerializedProperty = null;
+                var serializedProperty = state.serializedObject
+                    .FindProperty(nameof(InputActionAsset.m_ControlSchemes));
+                
+                if (state.selectedControlSchemeIndex < serializedProperty.arraySize)
+                {
+                    controlSchemeSerializedProperty = state.selectedControlSchemeIndex == -1 ? null :
+                        serializedProperty
+                            .GetArrayElementAtIndex(state.selectedControlSchemeIndex);
+                }
 
                 if (controlSchemeSerializedProperty == null)
                 {

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/Views/ControlSchemesView.cs

@@ -108,7 +108,6 @@ private void RemoveDeviceRequirement()
         public override void RedrawUI(InputControlScheme viewState)
         {
             rootElement.Q<TextField>(kControlSchemeNameTextField).value = string.IsNullOrEmpty(m_NewName) ? viewState.name : m_NewName;
-
             m_ListView.itemsSource?.Clear();
             m_ListView.itemsSource = viewState.deviceRequirements.Count > 0 ?
                 viewState.deviceRequirements.Select(r => (r.controlPath, r.isOptional)).ToList() :
@@ -128,7 +127,7 @@ private void SaveAndClose()
             CloseView();
         }
 
-        private void Cancel()
+        internal void Cancel()
         {
             // Reload the selected ControlScheme values from the SerilaizedProperty and throw away any changes
             Dispatch(ControlSchemeCommands.ResetSelectedControlScheme());

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/Views/InputActionsEditorView.cs

@@ -23,6 +23,8 @@ internal class InputActionsEditorView : ViewBase<InputActionsEditorView.ViewStat
         private readonly ToolbarButton m_SaveButton;
 
         private readonly Action m_SaveAction;
+        
+        private ControlSchemesView m_ControlSchemesView;
 
         public InputActionsEditorView(VisualElement root, StateContainer stateContainer, bool isProjectSettings,
                                       Action saveAction)
@@ -91,7 +93,7 @@ public InputActionsEditorView(VisualElement root, StateContainer stateContainer,
 
             // only register the state changed event here in the parent. Changes will be cascaded
             // into child views.
-            stateContainer.StateChanged += OnStateChanged;
+            stateContainer.StateChanged += StateChanged(stateContainer);
 
             CreateSelector(
                 s => s.selectedControlSchemeIndex,
@@ -106,6 +108,22 @@ public InputActionsEditorView(VisualElement root, StateContainer stateContainer,
             s_OnPasteCutElements.Add(this);
         }
 
+        private Action<InputActionsEditorState, UIRebuildMode> StateChanged(StateContainer stateContainer)
+        {
+            return (inputActionsEditorState, uiRebuildMode) =>
+            {
+                var state = stateContainer.GetState();
+                var viewState = ViewStateSelector.GetViewState(state);
+                var elementAtOrDefault = viewState.controlSchemes?.ElementAtOrDefault(viewState.selectedControlSchemeIndex);
+                if (viewState.selectedControlSchemeIndex != -1 && elementAtOrDefault == default(InputControlScheme))
+                {
+                    m_ControlSchemesView?.Cancel();
+                }
+                
+                OnStateChanged(inputActionsEditorState, uiRebuildMode);
+            };
+        }
+
         private void OnReset()
         {
             Dispatch(Commands.ReplaceActionMaps(ProjectWideActionsAsset.GetDefaultAssetJson()));
@@ -156,9 +174,8 @@ private void SetUpControlSchemesMenu(ViewState viewState)
 
             if (viewState.controlSchemes.Any())
             {
-                m_ControlSchemesToolbar.text = viewState.selectedControlSchemeIndex == -1
-                    ? "All Control Schemes"
-                    : viewState.controlSchemes.ElementAt(viewState.selectedControlSchemeIndex).name;
+                var elementAtOrDefault = viewState.controlSchemes.ElementAtOrDefault(viewState.selectedControlSchemeIndex);
+                m_ControlSchemesToolbar.text = elementAtOrDefault == default ? "All Control Schemes" : elementAtOrDefault.name;
 
                 m_ControlSchemesToolbar.menu.AppendAction("All Control Schemes", _ => SelectControlScheme(-1),
                     viewState.selectedControlSchemeIndex == -1 ? DropdownMenuAction.Status.Checked : DropdownMenuAction.Status.Normal);
@@ -186,7 +203,7 @@ private void SetUpDevicesMenu(ViewState viewState)
                 return;
             }
             m_DevicesToolbar.SetEnabled(true);
-            var currentControlScheme = viewState.controlSchemes.ElementAt(viewState.selectedControlSchemeIndex);
+            var currentControlScheme = viewState.controlSchemes.ElementAtOrDefault(viewState.selectedControlSchemeIndex);
             if (viewState.selectedDeviceIndex == -1)
                 m_DevicesToolbar.text = "All Devices";
 
@@ -228,12 +245,15 @@ private void DeleteControlScheme(DropdownMenuAction obj)
 
         private void ShowControlSchemeEditor(VisualElement parent, bool updateExisting = false)
         {
-            var controlSchemesView = CreateChildView(new ControlSchemesView(parent, stateContainer, updateExisting));
-            controlSchemesView.UpdateView(stateContainer.GetState());
-
-            controlSchemesView.OnClosing += _ => DestroyChildView(controlSchemesView);
+            m_ControlSchemesView = CreateChildView(new ControlSchemesView(parent, stateContainer, updateExisting));
+            m_ControlSchemesView.UpdateView(stateContainer.GetState());
+            m_ControlSchemesView.OnClosing += _ =>
+            {
+                DestroyChildView(m_ControlSchemesView);
+                m_ControlSchemesView = null;
+            };
         }
-
+        
         private void SelectControlScheme(int controlSchemeIndex)
         {
             Dispatch(ControlSchemeCommands.SelectControlScheme(controlSchemeIndex));