Make this[int] throw on dictionaries

Author: xPaw

ValveKeyValue/ValveKeyValue.Test/EdgeCaseTestCase.cs

@@ -732,9 +732,8 @@ public void DictAndListCollectionsHaveConsistentBehavior()
                 Assert.That(dict.Count, Is.EqualTo(2));
                 Assert.That(list.Count, Is.EqualTo(2));
 
-                // Integer indexer
-                Assert.That((int)dict[0], Is.EqualTo(1));
-                Assert.That((int)dict[1], Is.EqualTo(2));
+                // Integer indexer (list-backed only)
+                Assert.That(() => dict[0], Throws.InstanceOf<NotSupportedException>());
                 Assert.That((int)list[0], Is.EqualTo(1));
                 Assert.That((int)list[1], Is.EqualTo(2));
             });

ValveKeyValue/ValveKeyValue/KVObject.cs

@@ -197,7 +197,7 @@ public KVObject this[string key]
         }
 
         /// <summary>
-        /// Gets a child by index (for arrays and collections by insertion order).
+        /// Gets a child by index (for arrays and list-backed collections).
         /// </summary>
         public KVObject this[int index]
         {
@@ -208,12 +208,12 @@ public KVObject this[int index]
                     return GetArrayList()[index];
                 }
 
-                if (ValueType == KVValueType.Collection)
+                if (_ref is List<KeyValuePair<string, KVObject>> list && ValueType == KVValueType.Collection)
                 {
-                    return GetCollectionByIndex(index);
+                    return list[index].Value;
                 }
 
-                throw new NotSupportedException($"Integer indexer on a {nameof(KVObject)} can only be used when the value is an array or collection.");
+                throw new NotSupportedException($"Integer indexer on a {nameof(KVObject)} can only be used when the value is an array or list-backed collection.");
             }
         }
 
@@ -582,13 +582,6 @@ private bool TryInsert(string key, KVObject value, InsertionBehavior behavior)
             _ => [],
         };
 
-        private KVObject GetCollectionByIndex(int index) => _ref switch
-        {
-            Dictionary<string, KVObject> dict => dict.Values.ElementAt(index),
-            List<KeyValuePair<string, KVObject>> list => list[index].Value,
-            _ => throw new InvalidOperationException("Not a collection."),
-        };
-
         private IEnumerable<KeyValuePair<string, KVObject>> EnumerateArray()
         {
             var list = GetArrayList();