Created Unassigned: Unhandled Exception when creating a new work item that doesn't exist [45]

I was deleting work item types such as Impediment that I don't want cluttering my project lists. After refreshing and restarting, TFS WorkBench is still showing Impediment under the Item List tab. I figured bad things would happen if I clicked it and this is what I got. While handling the issue would be good, not showing the invalid work item types would be preferred.

An unhandled exception has occured and the application needs to close. Exception details:

The specified work item type cannot be found.

Save exception details to file?

at TfsWorkbench.TFSDataProvider2012.DataProvider.CreateValueProvider(IProjectData projectData, String typeName)
at TfsWorkbench.Core.WorkbenchItemGenerators.WorkbenchItemCreatorBase.GenerateNewInstance(String typeName)
at TfsWorkbench.WpfUI.Controllers.CommandController.OnCreateParent(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.CommandBinding.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.CommandManager.ExecuteCommandBinding(Object sender, ExecutedRoutedEventArgs e, CommandBinding commandBinding)
at System.Windows.Input.CommandManager.FindCommandBinding(CommandBindingCollection commandBindings, Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
at System.Windows.Input.CommandManager.FindCommandBinding(Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
at System.Windows.Input.CommandManager.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.Input.RoutedCommand.ExecuteImpl(Object parameter, IInputElement target, Boolean userInitiated)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)