Sourcetree fails to launch on invalid dictionaries

SourceTree 2.0.13-beta-1 silently crashes on launch when there are invalid dictionary files; following stack trace has been produced: ERROR [2017-03-20 10:41:20,630] [1] [SourceTree.App] [OnStartup] - Failed to start System.ArgumentException: Cannot set Owner property to itself. at System.Windows.Window.set_Owner(Window value) at SourceTree.Notifications.NotificationsManager.ShowNotificationDialog [T] (NotificationDialogWindow notificationWindow, Tuple`2 customAction, VistaTaskDialogIcon icon) at SourceTree.Notifications.NotificationsManager.ShowNotificationDialog [T] (String title, String message, Tuple`2 customAction, String cancelLabel, String suppressionSetting, Action`1 suppressionChangedAction, Object contentControl, String contentCommandLabel, Action contentAction) at SourceTree.Notifications.NotificationsManager.ShowNotificationDialogWithYesConfirmation(String title, String message, String details) at SourceTree.Configuration.WpfSpellCheckerPreFlightCheck.Run() at SourceTree.AppRoot.RunPreFlightChecks() at SourceTree.AppRoot.OnStartup(StartupEventArgs e) at SourceTree.App.OnStartup(StartupEventArgs e) DEBUG [2017-03-20 10:41:20,633] [3] [SourceTree.Instances.SingleInstance] [PipeConnectionReceived] - SingleInstance pipe connection received DEBUG [2017-03-20 10:41:20,637] [3] [SourceTree.Instances.SingleInstance] [StartServer] - SingleInstance waiting for connection: iar is not null{code} Opening an earlier version of SourceTree (eg. 1.9.10 or even Beta 12) will pop up the Invalid Dictionaries-dialog, after confirming the popup, ST 2.0.13 boots as usual.