[Fix] Null Ref Exception due to IsAssetEditable (#221)

* Resource can be null on a block inspector while we are removing it

Use safe check of resource before IsAssetEditable

* *Update changelog

* Fix issue https://github.cds.internal.unity3d.com/unity/vfx-graphics/pull/221#discussion_r113060

Author: PaulDemeulenaere

com.unity.visualeffectgraph/CHANGELOG.md

@@ -41,6 +41,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Safe Normalization of Cross Products in Orient blocks [Case 1272724](https://issuetracker.unity3d.com/product/unity/issues/guid/1272724)
 - Property Binder : Undo after reset [Case 1293794](https://issuetracker.unity3d.com/product/unity/issues/guid/1293794/)
 - Property Binder : Allow copy/past from a game object to another
+- Deleting a context node and a block while both are selected throws a null ref exception. [Case 315578](https://issuetracker.unity3d.com/product/unity/issues/guid/1315578/)
 
 ## [11.0.0] - 2020-10-21
 

com.unity.visualeffectgraph/Editor/Debug/VFXUIDebug.cs

@@ -838,7 +838,7 @@ void AddSystemInfoEntry(string systemName, int id, Color color)
                 var maxAliveButton = new Button();
                 maxAliveButton.name = "debug-system-stat-entry";
                 maxAliveButton.text = "0";
-                maxAliveButton.SetEnabled(m_Graph.visualEffectResource.IsAssetEditable());
+                maxAliveButton.SetEnabled(m_Graph.visualEffectResource != null && m_Graph.visualEffectResource.IsAssetEditable());
                 maxAliveButton.clickable.clickedWithEventInfo += setCapacity;
                 maxAlive = maxAliveButton;
             }
@@ -937,7 +937,7 @@ Action<EventBase> CapacitySetter(string systemName, out bool isSystemInSubGraph)
                     isSystemInSubGraph = true;
                     return (e) =>
                     {
-                        if (!m_Graph.visualEffectResource.IsAssetEditable())
+                        if (m_Graph.visualEffectResource != null && !m_Graph.visualEffectResource.IsAssetEditable())
                             return; //The button should be disabled but state update can have a delay
 
                         var button = e.currentTarget as Button;
@@ -957,7 +957,7 @@ void UpdateSystemInfoEntry(int systemId, VFXParticleSystemInfo stat)
                 alive.text = stat.aliveCount.ToString();
             if (statUI[4] is TextElement maxAliveText)
             {
-                maxAliveText.SetEnabled(m_Graph.visualEffectResource.IsAssetEditable());
+                maxAliveText.SetEnabled(m_Graph.visualEffectResource != null && m_Graph.visualEffectResource.IsAssetEditable());
                 maxAliveText.text = Mathf.Max(int.Parse(maxAliveText.text), stat.aliveCount).ToString();
             }
             if (statUI[5] is TextElement efficiency)

com.unity.visualeffectgraph/Editor/GraphView/Views/VFXView.cs

@@ -901,7 +901,7 @@ void ControllerChanged(int change)
 
         public bool IsAssetEditable()
         {
-            return controller.model.IsAssetEditable();
+            return controller.model != null && controller.model.IsAssetEditable();
         }
 
         void NewControllerSet()

com.unity.visualeffectgraph/Editor/Inspector/VFXParameterEditor.cs

@@ -47,7 +47,8 @@ public override SerializedProperty DoInspectorGUI()
         var saveEnabled = GUI.enabled;
 
         var referenceModel = serializedObject.targetObject as VFXModel;
-        if (!referenceModel.GetResource().IsAssetEditable())
+        var resource = referenceModel.GetResource();
+        if (resource != null && !resource.IsAssetEditable())
         {
             GUI.enabled = false;
             saveEnabled = false;

com.unity.visualeffectgraph/Editor/Inspector/VFXSlotContainerEditor.cs

@@ -229,7 +229,9 @@ public override void OnInspectorGUI()
     {
         serializedObject.Update();
         var referenceModel = serializedObject.targetObject as VFXModel;
-        GUI.enabled = referenceModel.GetResource().IsAssetEditable();
+
+        var resource = referenceModel.GetResource();
+        GUI.enabled = resource != null ? resource.IsAssetEditable() : true;
 
         SerializedProperty modifiedProperty = DoInspectorGUI();
 

com.unity.visualeffectgraph/Editor/Models/Contexts/Implementations/VFXBasicSpawner.cs

@@ -82,7 +82,8 @@ public override void OnInspectorGUI()
             serializedObject.Update();
 
             var referenceContext = serializedObject.targetObject as VFXContext;
-            GUI.enabled = referenceContext.GetResource().IsAssetEditable();
+            var resource = referenceContext.GetResource();
+            GUI.enabled = resource != null ? resource.IsAssetEditable() : true;
 
             EditorGUI.BeginChangeCheck();
             EditorGUILayout.PropertyField(m_LoopDurationProperty);

com.unity.visualeffectgraph/Editor/Models/Contexts/Implementations/VFXBasicUpdate.cs

@@ -69,7 +69,8 @@ public override void OnInspectorGUI()
             serializedObject.Update();
 
             var referenceContext = serializedObject.targetObject as VFXContext;
-            GUI.enabled = referenceContext.GetResource().IsAssetEditable();
+            var resource = referenceContext.GetResource();
+            GUI.enabled = resource != null ? resource.IsAssetEditable() : true;
 
             DisplaySpace();
             DisplayName();