NullReferenceException in WalkContext on Trace line

[chillitom]

Added StaticFile example to HelloWorldVNext and got the following error:

    1> KRE_TRACE=1 k web
    /Users/tom/.kre/packages/KRE-mono45-x86.0.1-alpha-build-0469/bin/Microsoft.Framework.Runtime.dll Information : 0 : Project root is /Users/tom/HelloWorldVNext/src/helloworldweb
    /Users/tom/.kre/packages/KRE-mono45-x86.0.1-alpha-build-0469/bin/Microsoft.Framework.Runtime.dll Information : 0 : Walking dependency graph for 'helloworldweb .NETFramework,Version=v4.5'.
    /Users/tom/.kre/packages/KRE-mono45-x86.0.1-alpha-build-0469/bin/Microsoft.Framework.Runtime.dll Information : 0 : [ProjectReferenceDependencyProvider]: helloworldweb 1.0.0, Nowin.vNext 1.0.0
    /Users/tom/.kre/packages/KRE-mono45-x86.0.1-alpha-build-0469/bin/Microsoft.Framework.Runtime.dll Information : 0 : [NuGetDependencyResolver]: Microsoft.AspNet.Http 0.1-alpha-build-0475, Microsoft.AspNet.FileSystems 0.1-alpha-build-0163, Nowin 0.11.0.0, Microsoft.AspNet.Hosting 0.1-alpha-build-0620, Microsoft.AspNet.Owin 0.1-alpha-build-0475, Microsoft.AspNet.FeatureModel 0.1-alpha-build-0475, Microsoft.AspNet.PipelineCore 0.1-alpha-build-0475, Microsoft.AspNet.Security.DataProtection 0.1-alpha-build-0154, Microsoft.Framework.ConfigurationModel 0.1-alpha-build-0245, Microsoft.Framework.DependencyInjection 0.1-alpha-build-0409, Microsoft.Framework.Logging 0.1-alpha-build-0179, Microsoft.Framework.Runtime.Interfaces 0.1-alpha-build-0469, Microsoft.AspNet.HttpFeature 0.1-alpha-build-0475
    System.NullReferenceException: Object reference not set to an instance of an object
      at Microsoft.Framework.Runtime.Library.ToString () [0x00000] in <filename unknown>:0 
      at System.String.Join[Library] (System.String separator, IEnumerable`1 values) [0x00000] in <filename unknown>:0 
      at Microsoft.Framework.Runtime.WalkContext.Populate (System.Runtime.Versioning.FrameworkName frameworkName, IList`1 libraries) [0x00000] in <filename unknown>:0 
      at Microsoft.Framework.Runtime.DependencyWalker.Walk (System.String name, NuGet.SemanticVersion version, System.Runtime.Versioning.FrameworkName targetFramework) [0x00000] in <filename unknown>:0 
      at Microsoft.Framework.Runtime.DefaultHost.GetEntryPoint (System.String applicationName) [0x00000] in <filename unknown>:0 
      at Microsoft.Framework.ApplicationHost.Program.ExecuteMain (Microsoft.Framework.Runtime.DefaultHost host, System.String applicationName, System.String[] args) [0x00000] in <filename unknown>:0 
      at Microsoft.Framework.ApplicationHost.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0 

project.json as follows:

            {
        "dependencies": {
            "Microsoft.AspNet.Http": "0.1-alpha-*",
            "Microsoft.AspNet.FileSystems": "0.1-alpha-*",
            "Microsoft.AspNet.StaticFiles": "",
            "Nowin.vNext": ""
        },
        "commands": {
            "web": "Microsoft.AspNet.Hosting --server Nowin.vNext"
        }
    }

[davidfowl]

This was a result of 18dedd6 change. Fixed.