Construct EnumContextDataItems on demand. Also, don't access their properties...

Construct EnumContextDataItems on demand.  Also, don't access their properties before checking for null.

src/ExpressionEvaluator/Core/Source/ResultProvider/Helpers/EvalResultDataItem.cs

@@ -36,7 +36,6 @@ internal sealed class EvalResultDataItem : DkmDataItem
         public readonly DkmEvaluationResultCategory Category;
         public readonly DkmEvaluationResultFlags Flags;
         public readonly string EditableValue;
-        public readonly EnumContextDataItem EnumContextDataItem;
 
         public string FullName
         {
@@ -83,7 +82,6 @@ public string FullName
             this.EditableValue = editableValue;
             this.Flags = flags | GetFlags(value) | ((expansion == null) ? DkmEvaluationResultFlags.None : DkmEvaluationResultFlags.Expandable);
             this.Expansion = expansion;
-            this.EnumContextDataItem = new EnumContextDataItem(this);
         }
 
         private static DkmEvaluationResultFlags GetFlags(DkmClrValue value)

src/ExpressionEvaluator/Core/Source/ResultProvider/ResultProvider.cs

@@ -89,7 +89,7 @@ void IDkmClrResultProvider.GetItems(DkmEvaluationResultEnumContext enumContext,
         {
             try
             {
-                var dataItem = enumContext.GetDataItem<EnumContextDataItem>().EvalResultDataItem;
+                var dataItem = enumContext.GetDataItem<EnumContextDataItem>();
                 if (dataItem == null)
                 {
                     // We don't know about this result.  Call next implementation
@@ -97,7 +97,7 @@ void IDkmClrResultProvider.GetItems(DkmEvaluationResultEnumContext enumContext,
                     return;
                 }
 
-                completionRoutine(GetItems(enumContext.InspectionContext, dataItem, startIndex, count));
+                completionRoutine(GetItems(enumContext.InspectionContext, dataItem.EvalResultDataItem, startIndex, count));
             }
             catch (Exception e) when (ExpressionEvaluatorFatalError.CrashIfFailFastEnabled(e))
             {
@@ -420,7 +420,7 @@ private DkmGetChildrenAsyncResult GetChildren(DkmInspectionContext inspectionCon
             var rows = builder.ToArrayAndFree();
             Debug.Assert(index >= rows.Length);
             Debug.Assert(initialRequestSize >= rows.Length);
-            var enumContext = DkmEvaluationResultEnumContext.Create(index, evaluationResult.StackFrame, evaluationResult.InspectionContext, dataItem.EnumContextDataItem);
+            var enumContext = DkmEvaluationResultEnumContext.Create(index, evaluationResult.StackFrame, evaluationResult.InspectionContext, new EnumContextDataItem(dataItem));
             return new DkmGetChildrenAsyncResult(rows, enumContext);
         }