Crash When Attempting to Add Existing Streaming Levels Already Present in the Levels Window

  235       	/**
  236       	 * Return whether this level should be visible/ associated with the world if it is
  237       	 * loaded.
  238       	 * 
  239       	 * @return true if the level should be visible, false otherwise
  240       	 */
  241       	virtual bool ShouldBeVisible() const;
  242       
  243       	virtual bool ShouldBeAlwaysLoaded() const { return false; }
  244       	
  245       	/** Get a bounding box around the streaming volumes associated with this LevelStreaming object */
  246       	FBox GetStreamingVolumeBounds();
  247       
  248       	/** Gets a pointer to the LoadedLevel value */
  249 ***** 	ENGINE_API class ULevel* GetLoadedLevel() const { return LoadedLevel; }
  250       	
  251       	/** Sets the LoadedLevel value to NULL */
  252       	void ClearLoadedLevel() { SetLoadedLevel(nullptr); }
  253       	
  254       #if WITH_EDITOR
  255       	/** Override Pre/PostEditUndo functions to handle editor transform */
  256       	virtual void PreEditUndo() override;
  257       	virtual void PostEditUndo() override;
  258       #endif
  259       	
  260       	/** Matcher for searching streaming levels by PackageName */
  261       	struct FPackageNameMatcher
  262       	{
  263       		FPackageNameMatcher( const FName& InPackageName )
  264       			: PackageName( InPackageName )

UE4Editor_Engine!ULevelStreaming::GetLoadedLevel() [levelstreaming.h:250]
UE4Editor_UnrealEd!UEditorLevelUtils::AddLevelsToWorld() [editorlevelutils.cpp:217]
UE4Editor_WorldBrowser!FStreamingLevelCollectionModel::HandleAddExistingLevelSelected() [streaminglevelcollectionmodel.cpp:458]
UE4Editor_WorldBrowser!TBaseSPMethodDelegateInstance<0,FStreamingLevelCollectionModel,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:327]
UE4Editor_WorldBrowser!TBaseSPMethodDelegateInstance<0,FStreamingLevelCollectionModel,0,void __cdecl() [delegateinstancesimpl.h:434]
UE4Editor_UnrealEd!`FEditorFileUtils::OpenLevelPickingDialog'::`2'::FLocal::OnLevelsSelected() [filehelpers.cpp:1807]
UE4Editor_UnrealEd!TBaseStaticDelegateInstance<void __cdecl() [delegateinstancesimpl.h:1027]
UE4Editor_ContentBrowser!SAssetDialog::OnConfirmClicked() [sassetdialog.cpp:821]
UE4Editor_ContentBrowser!TMemberFunctionCaller<SAssetDialog,FReply() [delegateinstanceinterface.h:165]
UE4Editor_ContentBrowser!UE4Tuple_Private::TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<SAssetDialog,FReply() [tuple.h:497]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SAssetDialog,0,FReply __cdecl() [delegateinstancesimpl.h:327]
UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [delegatesignatureimpl.inl:537]
UE4Editor_Slate!SButton::OnMouseButtonUp() [sbutton.cpp:282]
UE4Editor_Slate!<lambda_1002768c627006711ef2f351a87ec0e7>::operator() [slateapplication.cpp:5199]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_1002768c627006711ef2f351a87ec0e7> >() [slateapplication.cpp:232]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [slateapplication.cpp:5188]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [slateapplication.cpp:5690]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [slateapplication.cpp:5670]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1718]
UE4Editor_Core!FWindowsApplication::DeferMessage() [windowsapplication.cpp:2161]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [windowsapplication.cpp:881]
UE4Editor_Core!FWindowsApplication::AppWndProc() [windowsapplication.cpp:721]
user32!UserCallWinProcCheckWow()
user32!DispatchMessageWorker()
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [windowsplatformmisc.cpp:1009]
UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3151]
UE4Editor!GuardedMain() [launch.cpp:166]
UE4Editor!GuardedMainWrapper() [launchwindows.cpp:134]
UE4Editor!WinMain() [launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [exe_common.inl:253]
kernel32!BaseThreadInitThunk()
ntdll!RtlUserThreadStart()