Manually ported fixes from #4082

Author: Sergio0694

Microsoft.Toolkit.Mvvm/Messaging/Internals/ConditionalWeakTable2{TKey,TValue}.cs

@@ -129,6 +129,8 @@ public bool MoveNext()
 
                 while (node is not null)
                 {
+                    LinkedListNode<WeakReference<TKey>>? nextNode = node.Next;
+
                     // Get the key and value for the current node
                     if (node.Value.TryGetTarget(out TKey? target) &&
                         this.owner.table.TryGetValue(target!, out TValue? value))
@@ -144,7 +146,7 @@ public bool MoveNext()
                         this.owner.keys.Remove(node);
                     }
 
-                    node = node.Next;
+                    node = nextNode;
                 }
 
                 return false;