Fix U4-2320 - Error on saving User Permissions

Nodes can be null but NodeIds property always returns a collection and this will return Ids from Nodes if _nodeIds are null and Nodes is not.

src/Umbraco.Web/Cache/CacheRefresherEventHandler.cs

@@ -402,7 +402,7 @@ namespace Umbraco.Web.Cache
             {
                 DistributedCache.Instance.RefreshUserCache(sender.UserId);
             }
-            if (sender.Nodes.Any())
+            if (sender.NodeIds.Any())
             {
                 DistributedCache.Instance.RefreshAllUserCache();
             }