Im getting this on AppHarbor

gistfile1.txt

Server Error in '/' Application.

Value cannot be null.
Parameter name: key

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.ArgumentNullException: Value cannot be null.
Parameter name: key

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: 

gistfile2.cs

[ArgumentNullException: Value cannot be null.
Parameter name: key]
   System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory) +136
   Nancy.ViewEngines.DefaultViewCache.GetOrAdd(ViewLocationResult viewLocationResult, Func`2 valueFactory) +187
   Nancy.ViewEngines.Razor.RazorViewEngine.GetOrCompileView(ViewLocationResult viewLocationResult, IRenderContext renderContext, Assembly referencingAssembly, Type passedModelType) +137
   System.Dynamic.UpdateDelegates.UpdateAndExecute5(CallSite site, T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4) +852
   CallSite.Target(Closure , CallSite , RazorViewEngine , ViewLocationResult , IRenderContext , Assembly , Object ) +379
   Nancy.ViewEngines.Razor.RazorViewEngine.GetViewInstance(ViewLocationResult viewLocationResult, IRenderContext renderContext, Assembly referencingAssembly, Object model) +688
   System.Dynamic.UpdateDelegates.UpdateAndExecute5(CallSite site, T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4) +852
   Nancy.ViewEngines.Razor.<>c__DisplayClass1f.<RenderView>b__1e(Stream stream) +1687
   Nancy.Hosting.Aspnet.NancyHandler.SetNancyResponseToHttpResponse(HttpContextBase context, Response response) +124
   Nancy.Hosting.Aspnet.NancyHandler.ProcessRequest(HttpContextBase context) +69
   Nancy.Hosting.Aspnet.NancyHttpRequestHandler.ProcessRequest(HttpContext context) +63
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +876
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +162

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.18034