I get this YSOD from time to time in http://nerdbeers.apphb.com

YSOD in inerdbeers.txt

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.]
   Simple.Data.SimpleRecord.TryGetMember(GetMemberBinder binder, Object& result) in C:\Projecten\Org.NerdBeers\Dependencies\Simple.Data\Simple.Data\SimpleRecord.cs:48
   CallSite.Target(Closure , CallSite , Object ) +130
   Org.NerdBeers.Web.Services.Repository.GetBeerEventSubscribers(Int32 id) in d:\temp\rerb1bhw.i0j\input\src\Org.NerdBeers\Org.NerdBeers.Web\Services\Repository.cs:36
   Org.NerdBeers.Web.Modules.<>c__DisplayClass74.<.ctor>b__67(Object x) in d:\temp\rerb1bhw.i0j\input\src\Org.NerdBeers\Org.NerdBeers.Web\Modules\BeerEventModule.cs:26
   Nancy.Routing.Route.Invoke(DynamicDictionary parameters) in C:\Projecten\Nancy\Nancy\src\Nancy\Routing\Route.cs:29
   Nancy.NancyEngine.ResolveAndInvokeRoute(NancyContext context) in C:\Projecten\Nancy\Nancy\src\Nancy\NancyEngine.cs:119
   Nancy.NancyEngine.HandleRequest(Request request) in C:\Projecten\Nancy\Nancy\src\Nancy\NancyEngine.cs:85
   Nancy.Hosting.Aspnet.NancyHandler.ProcessRequest(HttpContextBase context) in C:\Projecten\Nancy\Nancy\src\Nancy.Hosting.Aspnet\NancyHandler.cs:19
   Nancy.Hosting.Aspnet.NancyHttpRequestHandler.ProcessRequest(HttpContext context) in C:\Projecten\Nancy\Nancy\src\Nancy.Hosting.Aspnet\NancyHttpRequestHandler.cs:76
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +100
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

Hehe, agreed. The repo was initially a singleton, but it was switched to per-request.
@grumpydev explained me the default convention for IOC: classes are per-request and interfaces are singletons.

Hi Tom.

Spent some time on this over lunch, was getting random tests not passing at random points, sometimes. I think I tracked the problem down to my BufferedEnumerable type and its blatant disregard for synchronization. I've added locking to it now, and run the tests several times with no fails. Could you try NB with a build from my latest master and see if the bug goes away? If so I'll push to NuGet as 0.5.2.

Thanks,
Mark

Hey Mark,

Thank you for the quick reaction; I'll try to do it ASAP...

Tom