Umbraco 6.1.4 URL Tracker 2.2.3

Any request for a non-existing URL results in the following error:

Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[NullReferenceException: Object reference not set to an instance of an object.]
   umbraco.presentation.UmbracoContext.GetXml() +17
   umbraco.NodeFactory.Node..ctor(Int32 NodeId) +164
   InfoCaster.Umbraco.UrlTracker.Modules.UrlTrackerModule.context_EndRequest(Object sender, EventArgs e) in c:\Users\kipusoep\Documents\GitHub\UrlTracker\Modules\UrlTrackerModule.cs:86
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +79
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +269

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272