Bug fix

https://github.com/2dust/v2rayN/issues/8720

v2rayN/ServiceLib/Common/Extension.cs

@@ -94,4 +94,28 @@ public static class Extension
     {
         return configType is EConfigType.Custom or EConfigType.PolicyGroup or EConfigType.ProxyChain;
     }
+
+    /// <summary>
+    /// Safely adds elements from a collection to the list. Does nothing if the source is null.
+    /// </summary>
+    public static void AddRangeSafe<T>(this ICollection<T> destination, IEnumerable<T>? source)
+    {
+        ArgumentNullException.ThrowIfNull(destination);
+
+        if (source is null)
+        {
+            return;
+        }
+
+        if (destination is List<T> list)
+        {
+            list.AddRange(source);
+            return;
+        }
+
+        foreach (var item in source)
+        {
+            destination.Add(item);
+        }
+    }
 }

v2rayN/ServiceLib/Manager/ActionPrecheckManager.cs

@@ -218,8 +218,8 @@ public class ActionPrecheckManager
 
         var childIds = new List<string>();
         var subItems = await ProfileGroupItemManager.GetSubChildProfileItems(group);
-        childIds.AddRange(subItems.Select(p => p.IndexId));
+        childIds.AddRangeSafe(subItems.Select(p => p.IndexId));
-        childIds.AddRange(Utils.String2List(group.ChildItems));
+        childIds.AddRangeSafe(Utils.String2List(group.ChildItems));
 
         foreach (var child in childIds)
         {