SWorldPartitionEditorGrid2D causing editor to crash

Should be reproducible with a blank project and EGL binary distribution of 5.1 (Windows) 

1. Create a new level, LevelA, with a cube in it.
2. Create a new World Partition Level, LevelB, and place and instance of LevelA in it.
3. Right Click on LevelA in the Content Browser, select Asset Actions and then Capture
Thumbnail.
4. Double Click on Level A in the Content browser to open it.
5. Press Save Selected in the ‘Save Content’ Dialog.
6. Press Continue in the Dialog shown due to the save failing.
7. Press Ok in the ‘Packages Failed to Save’ dialog
8. Press Ok in the Dialog stating that the modified Assets cannot be unloaded

Then the Engine should crash

[Inlined] UEditorEngine::Map_Load::__l88::<lambda_c863acb0507e397a7ab895ffd0dbf5aa>::operator()(const FLogCategoryLogEditorServer &,const wchar_t (&)[73],const int &) EditorServer.cpp:2642
DispatchCheckVerify<void,<lambda_c863acb0507e397a7ab895ffd0dbf5aa>,FLogCategoryLogEditorServer,wchar_t [73],int>(<lambda_c863acb0507e397a7ab895ffd0dbf5aa> &&,const FLogCategoryLogEditorServer &,const wchar_t (&)[73],const int &) AssertionMacros.h:171
UEditorEngine::Map_Load(const wchar_t *,FOutputDevice &) EditorServer.cpp:2642
UEditorEngine::HandleMapCommand(const wchar_t *,FOutputDevice &,UWorld *) EditorServer.cpp:6232
UEditorEngine::Exec(UWorld *,const wchar_t *,FOutputDevice &) EditorServer.cpp:5749
UUnrealEdEngine::Exec(UWorld *,const wchar_t *,FOutputDevice &) UnrealEdSrv.cpp:659
FEditorFileUtils::LoadMap(const FString &,bool,const bool) FileHelpers.cpp:2849
FAssetTypeActions_World::OpenAssetEditor(const TArray<UObject *,TSizedDefaultAllocator<32> > &,TSharedPtr<IToolkitHost,1>) AssetTypeActions_World.cpp:46
UAssetEditorSubsystem::OpenEditorForAsset(UObject *,Type,TSharedPtr<IToolkitHost,1>,const bool) AssetEditorSubsystem.cpp:402
UAssetEditorSubsystem::OpenEditorForAssets_Advanced(const TArray<UObject *,TSizedDefaultAllocator<32> > &,Type,TSharedPtr<IToolkitHost,1>) AssetEditorSubsystem.cpp:476
UAssetEditorSubsystem::OpenEditorForAssets(const TArray<UObject *,TSizedDefaultAllocator<32> > &) AssetEditorSubsystem.cpp:591
ContentBrowserAssetData::EditOrPreviewAssetFileItems(TArrayView<TSharedRef<FContentBrowserAssetFileItemDataPayload const ,1> const ,int>,const bool) ContentBrowserAssetDataCore.cpp:288
ContentBrowserAssetData::EditOrPreviewItems(IAssetTools *,const UContentBrowserDataSource *,TArrayView<FContentBrowserItemData const ,int>,const bool) ContentBrowserAssetDataCore.cpp:308
[Inlined] ContentBrowserAssetData::EditItems(IAssetTools *,const UContentBrowserDataSource *,TArrayView<FContentBrowserItemData const ,int>) ContentBrowserAssetDataCore.cpp:313
UContentBrowserAssetDataSource::BulkEditItems(TArrayView<FContentBrowserItemData const ,int>) ContentBrowserAssetDataSource.cpp:1237
SContentBrowser::OnItemsActivated(TArrayView<FContentBrowserItem const ,int>,Type) SContentBrowser.cpp:3020
[Inlined] Invoke(void (SContentBrowser::*)(TArrayView<FContentBrowserItem const ,int>, EAssetTypeActivationMethod::Type),SContentBrowser *&,TArrayView<FContentBrowserItem const ,int> &,EAssetTypeActivationMethod::Type &) Invoke.h:66
[Inlined] UE::Core::Private::Tuple::TTupleBase<TIntegerSequence<unsigned int> >::ApplyAfter(void (SContentBrowser::*&)(TArrayView<FContentBrowserItem const ,int>, EAssetTypeActivationMethod::Type),SContentBrowser *&,TArrayView<FContentBrowserItem const ,int> &,EAssetTypeActivationMethod::Type &) Tuple.h:327
TBaseSPMethodDelegateInstance<0,SContentBrowser,1,void __cdecl(TArrayView<FContentBrowserItem const ,int>,enum EAssetTypeActivationMethod::Type),FDefaultDelegateUserPolicy>::Execute(TArrayView<FContentBrowserItem const ,int>,Type) DelegateInstancesImpl.h:295
[Inlined] TDelegate<void __cdecl(TArrayView<FContentBrowserItem const ,int>,enum EAssetTypeActivationMethod::Type),FDefaultDelegateUserPolicy>::Execute(TArrayView<FContentBrowserItem const ,int>,Type) DelegateSignatureImpl.inl:620
SAssetView::OnListMouseButtonDoubleClick(TSharedPtr<FAssetViewItem,1>) SAssetView.cpp:3668
[Inlined] Invoke(void (SAssetView::*)(TSharedPtr<FAssetViewItem,1>),SAssetView *&,TSharedPtr<FAssetViewItem,1> &) Invoke.h:66
[Inlined] UE::Core::Private::Tuple::TTupleBase<TIntegerSequence<unsigned int> >::ApplyAfter(void (SAssetView::*&)(TSharedPtr<FAssetViewItem,1>),SAssetView *&,TSharedPtr<FAssetViewItem,1> &) Tuple.h:327
TBaseSPMethodDelegateInstance<0,SAssetView,1,void __cdecl(TSharedPtr<FAssetViewItem,1>),FDefaultDelegateUserPolicy>::ExecuteIfSafe(TSharedPtr<FAssetViewItem,1>) DelegateInstancesImpl.h:312
TDelegate<void __cdecl(TSharedPtr<FAssetViewItem,1>),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>(TSharedPtr<FAssetViewItem,1>) DelegateSignatureImpl.inl:639
SListView<TSharedPtr<FAssetViewItem,1> >::Private_OnItemDoubleClicked(TSharedPtr<FAssetViewItem,1>) SListView.h:1115
STableRow<TSharedPtr<FAssetViewItem,1> >::OnMouseButtonDoubleClick(const FGeometry &,const FPointerEvent &) STableRow.h:422
[Inlined] FSlateApplication::RoutePointerDoubleClickEvent::__l2::<lambda_be18c20258355610e1a03a230227eebb>::operator()(const FArrangedWidget &,const FPointerEvent &) SlateApplication.cpp:5528
FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FPointerEvent,<lambda_be18c20258355610e1a03a230227eebb> >(FSlateApplication *,FBubblePolicy,FPointerEvent,const <lambda_be18c20258355610e1a03a230227eebb> &,ESlateDebuggingInputEvent) SlateApplication.cpp:412
FSlateApplication::RoutePointerDoubleClickEvent(const FWidgetPath &,const FPointerEvent &) SlateApplication.cpp:5526
FSlateApplication::ProcessMouseButtonDoubleClickEvent(const TSharedPtr<FGenericWindow,1> &,const FPointerEvent &) SlateApplication.cpp:5509
FSlateApplication::OnMouseDoubleClick(const TSharedPtr<FGenericWindow,1> &,Type,TVector2<double>) SlateApplication.cpp:5474
FWindowsApplication::ProcessDeferredMessage(const FDeferredWindowsMessage &) WindowsApplication.cpp:2223
FWindowsApplication::DeferMessage(TSharedPtr<FWindowsWindow,1> &,HWND__ *,unsigned int,unsigned long long,long long,int,int,unsigned int) WindowsApplication.cpp:2726
FWindowsApplication::ProcessMessage(HWND__ *,unsigned int,unsigned long long,long long) WindowsApplication.cpp:1895
[Inlined] WindowsApplication_WndProc(HWND__ *,unsigned int,unsigned long long,long long) WindowsApplication.cpp:919
FWindowsApplication::AppWndProc(HWND__ *,unsigned int,unsigned long long,long long) WindowsApplication.cpp:924
<unknown> 0x00007ff91677e7e8
<unknown> 0x00007ff91677e47e
<unknown> 0x000001b185957e59
<unknown> 0x00007ff902a21028
<unknown> 0x00007ff91677e7e8
<unknown> 0x00007ff91677e229
[Inlined] WinPumpMessages() WindowsPlatformApplicationMisc.cpp:113
FWindowsPlatformApplicationMisc::PumpMessages(bool) WindowsPlatformApplicationMisc.cpp:142
FEngineLoop::Tick() LaunchEngineLoop.cpp:5285
[Inlined] EngineTick() Launch.cpp:66
GuardedMain(const wchar_t *) Launch.cpp:204
LaunchWindowsStartup(HINSTANCE__ *,HINSTANCE__ *,char *,int,const wchar_t *) LaunchWindows.cpp:233
WinMain(HINSTANCE__ *,HINSTANCE__ *,char *,int) LaunchWindows.cpp:282
[Inlined] invoke_main() 0x00007ff73fcaa516
__scrt_common_main_seh() 0x00007ff73fcaa4f5
<unknown> 0x00007ff9176b7614
<unknown> 0x00007ff9184c26a1