Validate that an instance has been created, via the instanceExists bool prop in IEditingContext, before attempting to dispose in EditingContextManager's SetEditingContext() function

Author: dunity

Scripts/Core/Contexts/EditingContextManager.cs

@@ -227,7 +227,9 @@ internal void SetEditingContext(IEditingContext context)
             if (s_CurrentContext != null)
             {
                 m_PreviousContexts.Insert(0, s_CurrentContext);
-                s_CurrentContext.Dispose();
+
+                if (s_CurrentContext.instanceExists)
+                    s_CurrentContext.Dispose();
             }
 
             context.Setup();

Scripts/Core/Contexts/EditorVRContext.cs

@@ -23,6 +23,8 @@ class EditorVRContext : ScriptableObject, IEditingContext
 
         public bool copySceneCameraSettings { get { return m_CopySceneCameraSettings; } }
 
+        public bool instanceExists { get { return m_Instance != null; } }
+
         public void Setup()
         {
             EditorVR.defaultTools = m_DefaultToolStack.Select(ms => ms.GetClass()).ToArray();
@@ -32,12 +34,9 @@ public void Setup()
 
         public void Dispose()
         {
-            if (m_Instance)
-            {
-                m_Instance.Shutdown(); // Give a chance for dependent systems (e.g. serialization) to shut-down before destroying
-                ObjectUtils.Destroy(m_Instance.gameObject);
-                m_Instance = null;
-            }
+            m_Instance.Shutdown(); // Give a chance for dependent systems (e.g. serialization) to shut-down before destroying
+            ObjectUtils.Destroy(m_Instance.gameObject);
+            m_Instance = null;
         }
     }
 }

Scripts/Interfaces/Entity/IEditingContext.cs

@@ -19,6 +19,11 @@ public interface IEditingContext
         /// </summary>
         bool copySceneCameraSettings { get; }
 
+        /// <summary>
+        /// Bool denotes that the EditorVR instance exists, having already been created in Setup()
+        /// </summary>
+        bool instanceExists { get; }
+
         /// <summary>
         /// Perform one-time setup for the context when pushed to the stack.
         /// </summary>