补个注释

Assets/Scripts/Manager/OperationManager.cs

@@ -58,13 +58,19 @@ namespace Ichni.Editor
             
             if (gameElement.parentElement != null)
             {
-                gameElement.parentElement.childElementList.Remove(gameElement);
+                gameElement.parentElement.childElementList.Remove(gameElement); //从父物体的子物体列表中移除，避免报null
             }
 
             gameElement.Delete();
         }
         
-        private GameElement AffiliatedPaste(GameElement gameElement, GameElement parent)
+        /// <summary>
+        /// 使用递归的方式复制粘贴物体及其所有子物体
+        /// </summary>
+        /// <param name="gameElement">将要被粘贴的物体</param>
+        /// <param name="parent">（将要）被粘贴物体的父物体</param>
+        /// <returns></returns>
+        private void AffiliatedPaste(GameElement gameElement, GameElement parent)
         {
             gameElement.SaveBM();
             GameElement pastedElement = (gameElement.matchedBM as GameElement_BM).DuplicateBM(parent);
@@ -82,8 +88,6 @@ namespace Ichni.Editor
                     AffiliatedPaste(gameElement.childElementList[i], pastedElement);
                 }
             }
-
-            return pastedElement;
         }
     }
 }