Address feedback

src/VisualStudio/Core/Def/Implementation/TableDataSource/TableItem.cs

@@ -30,26 +30,23 @@ public TableItem(T item, Func<T, int> keyGenerator)
 
         public TableItem(IEnumerable<TableItem<T>> items)
         {
-            var itemCount = items.Count();
-            if (itemCount == 0)
+            var first = true;
+            var collectionHash = 1;
+            var count = 0;
+
+            // Make things to be deterministic. 
+            var orderedItems = items.Where(i => i.PrimaryDocumentId != null).OrderBy(i => i.PrimaryDocumentId.Id).ToList();
+            if (orderedItems.Count == 0)
             {
                 // There must be at least 1 item in the list
                 FatalError.ReportWithoutCrash(new ArgumentException("Contains no items", nameof(items)));
             }
-
-            var filteredItems = items.Where(i => i.PrimaryDocumentId != null);
-            if (filteredItems.Count() != itemCount)
+            else if (orderedItems.Count != items.Count())
             {
                 // There must be document id for provided items.
                 FatalError.ReportWithoutCrash(new ArgumentException("Contains an item with null PrimaryDocumentId", nameof(items)));
             }
 
-            var first = true;
-            var collectionHash = 1;
-            var count = 0;
-
-            // Make things to be deterministic. 
-            var orderedItems = filteredItems.OrderBy(i => i.PrimaryDocumentId.Id);
             foreach (var item in orderedItems)
             {
                 count++;