Editor crashes if opening a sublevel containing a navmesh when persistent level is open

If the persistent level is open and a user attempts to open a sublevel that contains a navmesh, the editor will freeze and then crash.

Frequency: 3/3

Crashreporter: N/A

1. Open Editor (any project)
2. Create new level (default)
3. Add navmesh bounds volume and adjust around level
4. Save level
5. Create new level
6. Open Window>Levels>Levels>Add Existing>New Level (1)
7. Save
8. Open File>Open Level>New Level (1)

Results:

Editor freezes and crashes

Expected:

Editor opens first new level, does not crash or freeze.

MachineId:4E82586D46B558EA69EF0EAA821297B1
EpicAccountId:1558531203f84e81b70959b8a59badef

Unknown exception - code 00000001 (first/second chance not available)

"Fatal error: [Link Removed] [Line: 1773]
//Game//ThirdPersonBP//Maps//ThirdPersonExampleMap.ThirdPersonExa

UE4Editor_Core!FDebug::AssertFailed() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\private\misc\outputdevice.cpp:354]
UE4Editor_UnrealEd!UEditorEngine::CheckForWorldGCLeaks() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:1773]
UE4Editor_UnrealEd!UEditorEngine::EditorDestroyWorld() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:1903]
UE4Editor_UnrealEd!UEditorEngine::Map_Load() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:2255]
UE4Editor_UnrealEd!UEditorEngine::HandleMapCommand() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:5823]
UE4Editor_UnrealEd!UEditorEngine::Exec() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorserver.cpp:5317]
UE4Editor_UnrealEd!UUnrealEdEngine::Exec() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\unrealedsrv.cpp:743]
UE4Editor_UnrealEd!FEditorFileUtils::LoadMap() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\filehelpers.cpp:2014]
UE4Editor_AssetTools!FAssetTypeActions_World::OpenAssetEditor() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\developer\assettools\private\assettypeactions\assettypeactions_world.cpp:23]
UE4Editor_UnrealEd!FAssetEditorManager::OpenEditorForAsset() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\toolkits\asseteditormanager.cpp:303]
UE4Editor_AssetTools!FAssetTypeActions_Base::AssetsActivated() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\developer\assettools\public\assettypeactions_base.h:37]
UE4Editor_ContentBrowser!SContentBrowser::OnAssetsActivated() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\contentbrowser\private\scontentbrowser.cpp:1757]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SContentBrowser,0,TTypeWrapper<void> __cdecl(TArray<FAssetData,FDefaultAllocator> const & __ptr64,enum EAssetTypeActivationMethod::Type)>::Execute() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:282]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SContentBrowser,0,void __cdecl(TArray<FAssetData,FDefaultAllocator> const & __ptr64,enum EAssetTypeActivationMethod::Type)>::ExecuteIfSafe() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!SAssetView::OnListMouseButtonDoubleClick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\contentbrowser\private\sassetview.cpp:3287]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,TTypeWrapper<void> __cdecl(TSharedPtr<FAssetViewItem,0>)>::Execute() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:282]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetView,0,void __cdecl(TSharedPtr<FAssetViewItem,0>)>::ExecuteIfSafe() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:388]
UE4Editor_ContentBrowser!TBaseDelegate<void,TSharedPtr<FAssetViewItem,0> >::ExecuteIfBound() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:482]
UE4Editor_ContentBrowser!SListView<TSharedPtr<FAssetViewItem,0> >::Private_OnItemDoubleClicked() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\slate\public\widgets\views\slistview.h:689]
UE4Editor_ContentBrowser!STableRow<TSharedPtr<FAssetViewItem,0> >::OnMouseButtonDoubleClick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\slate\public\widgets\views\stablerow.h:261]
UE4Editor_Slate!<lambda_58ede244782f1e594383d45514e1d7c8>::operator()() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4606]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FPointerEvent,<lambda_58ede244782f1e594383d45514e1d7c8> >() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:214]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonDoubleClickEvent() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4607]
UE4Editor_Slate!FSlateApplication::OnMouseDoubleClick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4587]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:1345]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:1708]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:706]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsapplication.cpp:628]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:884]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launchengineloop.cpp:2392]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

Editor crashes when opening a level that is streamed and has a navmesh