[220] Exception when a .txt is open

I have a .txt file as solution item in my solution.
If I exit from VS with this .txt file opened and relaunch VS, when RS make the parse of the opened file I receive this exception:

 System.ArgumentNullException: Key cannot be null.
Parameter name: key
   at System.Collections.Hashtable.ContainsKey(Object key)
   at JetBrains.ReSharper.Util.WeakToStrongHashtable.ContainsKey(Object key) in c:\TEMP\tmpC621.tmp\src\Util\src\dataStructures\WeakToStrongHashtable.cs:line 112
   at JetBrains.ReSharper.Shell.Impl.ChangeManagerImpl.AddDependency(IChangeProvider provider, IChangeProvider dependsUpon) in c:\TEMP\tmpC621.tmp\src\Shell\src\impl\changes\ChangeManagerImpl.cs:line 520
   at JetBrains.VSAddin.TextControl.VSTextControl..ctor(ISolution solution, IVsTextView vsTextView) in c:\TEMP\tmpC621.tmp\src\VSAddin\src\TextControl\VSTextControl.cs:line 64
   at JetBrains.ReSharper.EditorManager.VSIntegration.VSEditorManager.RegisterView(IVsTextView view) in c:\TEMP\tmpC621.tmp\src\VSAddin\src\EditorManager\VSEditorManager.cs:line 154
   at JetBrains.ReSharper.EditorManager.VSIntegration.VSEditorManager.TextViewOpened(IVsTextView textView) in c:\TEMP\tmpC621.tmp\src\VSAddin\src\EditorManager\VSEditorManager.cs:line 134
   at JetBrains.ReSharper.Editor.VSIntegration.VSDocumentManager.RaiseTextViewOpened(IVsTextView textView) in c:\TEMP\tmpC621.tmp\src\VSAddin\src\Editor\VSDocumentManager.cs:line 623
   at JetBrains.ReSharper.Editor.VSIntegration.VSDocumentManager.OnNewTextView(IVsTextView textView) in c:\TEMP\tmpC621.tmp\src\VSAddin\src\Editor\VSDocumentManager.cs:line 617
   at JetBrains.ReSharper.Editor.VSIntegration.VSDocumentManager.AfterSolutionOpened() in c:\TEMP\tmpC621.tmp\src\VSAddin\src\Editor\VSDocumentManager.cs:line 931
   at JetBrains.ReSharper.ProjectModel.Impl.SolutionBase.AfterSolutionOpened() in c:\TEMP\tmpC621.tmp\src\ProjectModel\src\impl\SolutionBase.cs:line 189
   --- End of inner exception stack trace ---

	at JetBrains.ReSharper.Util.Logger.LogExceptionEx(Exception, String, Boolean) in c:\TEMP\tmpC621.tmp\src\Util\src\Logger.cs:line 297 column 9
	at JetBrains.ReSharper.Util.Logger.LogException(Exception) in c:\TEMP\tmpC621.tmp\src\Util\src\Logger.cs:line 309 column 5
	at JetBrains.ReSharper.ProjectModel.Impl.SolutionBase.AfterSolutionOpened() in c:\TEMP\tmpC621.tmp\src\ProjectModel\src\impl\SolutionBase.cs:line 193 column 11
	at JetBrains.ReSharper.ProjectModel.Impl.SolutionManagerBase.OpenSolutionInternal(SolutionImpl, ITaskExecutor) in c:\TEMP\tmpC621.tmp\src\ProjectModel\src\impl\SolutionManagerBase.cs:line 80 column 7
	at JetBrains.VSAddin.ProjectModel.VSSolutionManager.OpenCurrentSolution() in c:\TEMP\tmpC621.tmp\src\VSAddin\src\ProjectModel\VSSolutionManager.cs:line 867 column 11
	at JetBrains.VSAddin.ProjectModel.VSSolutionManager.OpenVSSolution(Boolean) in c:\TEMP\tmpC621.tmp\src\VSAddin\src\ProjectModel\VSSolutionManager.cs:line 366 column 11
	at JetBrains.VSAddin.ProjectModel._OnAfterOpenSolutionDelegatesClass._OnAfterOpenSolutionDelegate125() in c:\TEMP\tmpC621.tmp\src\VSAddin\src\ProjectModel\VSSolutionManager.cs:line 349 column 7
	at JetBrains.ReSharper.Shell.PendingAction.Execute() in c:\TEMP\tmpC621.tmp\src\Shell\src\Invocator.cs:line 235 column 11
	at JetBrains.ReSharper.Shell.Invocator.ProcessQueue() in c:\TEMP\tmpC621.tmp\src\Shell\src\Invocator.cs:line 167 column 11
	at System.Reflection.RuntimeMethodInfo.InternalInvoke(Object, BindingFlags, Binder, Object[], CultureInfo, Boolean, Assembly, Boolean)
	at System.Reflection.RuntimeMethodInfo.InternalInvoke(Object, BindingFlags, Binder, Object[], CultureInfo, Boolean)
	at System.Delegate.DynamicInvokeImpl(Object[])
	at System.MulticastDelegate.DynamicInvokeImpl(Object[])
	at System.Windows.Forms.Control.InvokeMarshaledCallbacks()
	at System.Windows.Forms.Control.WndProc(Message&)
	at System.Windows.Forms.ScrollableControl.WndProc(Message&)
	at System.Windows.Forms.ContainerControl.WndProc(Message&)
	at System.Windows.Forms.ParkingWindow.WndProc(Message&)
	at System.Windows.Forms.ControlNativeWindow.OnMessage(Message&)
	at System.Windows.Forms.ControlNativeWindow.WndProc(Message&)
	at System.Windows.Forms.NativeWindow.Callback(IntPtr, Int32, IntPtr, IntPtr)

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