Editor crashes when exiting and having a widget blueprint open.

This is a top crash occurring in the 4.11 Preview

Editor crashes when exiting and having a widget blueprint open.

Regression: Yes does not occur in 4.10.2.

1. Open a project
2. Create and open a widget blueprint
3. File > Exit

UE4Editor_SlateCore!FSlateApplicationBase::Get() slateapplicationbase.h:395
UE4Editor_SlateCore!SWidget::RegisterActiveTimer() swidget.cpp:699
UE4Editor_PropertyEditor!SDetailsView::ForceRefresh() sdetailsview.cpp:291
UE4Editor_PropertyEditor!FPropertyEditorModule::NotifyCustomizationModuleChanged() propertyeditormodule.cpp:109
UE4Editor_DetailCustomizations!FDetailCustomizationsModule::ShutdownModule() detailcustomizations.cpp:151
UE4Editor_Core!FModuleManager::UnloadModule() modulemanager.cpp:503
UE4Editor_Core!FModuleManager::UnloadModulesAtShutdown() modulemanager.cpp:627
UE4Editor!FEngineLoop::Exit() launchengineloop.cpp:2311
UE4Editor!GuardedMain() launch.cpp:153
UE4Editor!GuardedMainWrapper() launchwindows.cpp:126
UE4Editor!WinMain() launchwindows.cpp:200
UE4Editor!__scrt_common_main_seh() exe_common.inl:264
kernel32!<Unknown>
ntdll!<Unknown>