Edited Issue: Test Adapter crashes VS [694]

Here's the call stack from event viewer.

I used VS 2012 Update 4, Node.js 0.10.26 32-bit, with the New NPM UI build from Feb 25.
Make sure test adapter is open
Create New Express project
Click yes to install
While it installed in the command prompt window, VS crashed.

```
Application: devenv.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.NullReferenceException
Stack:
at Microsoft.NodejsTools.TestAdapter.TestContainerDiscoverer.IsTestFile(System.String)
at Microsoft.NodejsTools.TestAdapter.TestContainerDiscoverer.ShouldDiscover(System.String)
at Microsoft.NodejsTools.TestAdapter.TestContainerDiscoverer.OnProjectItemChanged(System.Object, Microsoft.VisualStudioTools.TestAdapter.TestFileChangedEventArgs)
at Microsoft.VisualStudioTools.TestAdapter.TestFilesUpdateWatcher.OnChanged(System.Object, System.IO.FileSystemEventArgs)
at System.IO.FileSystemWatcher.OnChanged(System.IO.FileSystemEventArgs)
at System.IO.FileSystemWatcher.NotifyFileSystemEventArgs(Int32, System.String)
at System.IO.FileSystemWatcher.CompletionStatusChanged(UInt32, UInt32, System.Threading.NativeOverlapped*)
at System.Threading._IOCompletionCallback.IOCompletionCallback_Context(System.Object)
at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32, UInt32, System.Threading.NativeOverlapped*)
```