修复:避免已经被移除的材质造成错误

src/DatabaseServices/Database.ts

@@ -287,7 +287,8 @@ export class Database
             {
                 let objectId = this.GetObjectId(idIndex, false);
                 let object = objectId.Object;
-
+                if (object === undefined)
+                    continue;//对象已经被删除
                 if (!object.Owner)
                 {
                     console.error("无主?");