NullReferenceException on corrupt peer when connecting

[gyorgy-giczi]

Hi,

We just ran into an issue during a C* meaintenence, when selecting from system.peers resulted some null values in DC and rack columns, which caused Cluster.GetNodeFromDataReader to return null, which caused NullReferenceException in Cluster.InDiscoveryScope(), so finally CqlConnection.Open() failed. I suggest to add the following check to Cluster.InDiscoveryScope()

    private bool InDiscoveryScope(Node reference, Node target, DiscoveryScope discoveryScope)
    {
        if (target == null)
        {
            return false;
        }

Thank you.