Putting exception message into NLog's Chainsaw log4j xml output

It doesn't appear possible to get exception infomation into the chainsaw target renderer, so I got around this by extending the Log4JXmlEventLayout and butchering the xml.

Chalk this one up as a nasty hack, it's not pretty.

[Target("ChainsawExtended")]
public class ChainsawExtendedTarget : ChainsawTarget
{
    private readonly Log4JXmlEventLayoutExtended _layout = new Log4JXmlEventLayoutExtended();

    public override Layout Layout
    {
        get { return _layout; }
        set { }
    }

    private class Log4JXmlEventLayoutExtended : Log4JXmlEventLayout
    {
        protected override string GetFormattedMessage(LogEventInfo logEvent)
        {
            string s = base.GetFormattedMessage(logEvent);
            if(logEvent.Exception == null)
            {
                return s;
            }
            s = s.Replace("<log4j:event", "<log4j:event xmlns:log4j=\"http://nlog-project.org/dummynamespace/\"");
            var element = XDocument.Parse(s);
            var messageElement = element.Descendants().Where(e => e.Name.LocalName == "message").Single();
            messageElement.Value += Environment.NewLine + logEvent.Exception;
            s = element.ToString();
            s = s.Replace(" xmlns:log4j=\"http://nlog-project.org/dummynamespace/\"", string.Empty);
            return s;
        }
    }
}