Ierrorhandler wcf msdn
true if Windows Communication Foundation (WCF) should not abort the session (if there is one) and instance context if the instance context is not Single; otherwise, false. The default is false.Implement the IErrorHandler interface in a base class for the 40 service classes. The biggest downside of this is that it will need to handle all the possible Fault Contracts defined throughout the various services. ierrorhandler wcf msdn
This is basically just the msdn example wrapped in a class that inherits IErrorHandler and IServiceBehaviour then this is wrapped in the Extension element that inherits from to allegedly allow me to add the element into the web. config.