fix warning by checking value for null before returning from TryPeek

Author: lodicolo

Framework/Intersect.Framework/Collections/ConcurrentConditionalDequeue.cs

@@ -119,7 +119,7 @@ public bool TryPeek([NotNullWhen(true)] out TValue? value)
     {
         lock (_dequeueLock)
         {
-            return _queue.TryPeek(out value);
+            return _queue.TryPeek(out value) && value != null;
         }
     }