Crash occurs when undoing the adding of a node connected to an in-use reroute node

REGRESSION Yes, this does not occur in 4.19.0 or in 4.18

Crash occurs when the user adds a node off a reroute node that's already in use, and then undoes that action.

Found when testing around [Link Removed]

1. Open QAGame in editor
2. Open the level blueprint.
3. Add a reference to the Sky Sphere actor in the graph.
4. Drag off it and add a Get Class node.
5. Drag off the Get Class and add a Get Class Defaults node.
6. Drag off the Refresh Materials bool and add a Branch node.
7. Double-click the wire between Get Class and Get Class Defaults, to add a reroute node.
8. Drag off the reroute node and add another Get Class Defaults node.
9. Undo.

RESULT

Crash.

Assertion failed: !PinRef->bWasTrashed [Link Removed] [Line: 1840]

KERNELBASE.dll!UnknownFunction []
UE4Editor-ApplicationCore.dll!FWindowsErrorOutputDevice::Serialize() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowserroroutputdevice.cpp:65]
UE4Editor-Core.dll!FOutputDevice::LogfImpl() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:70]
UE4Editor-Core.dll!FDebug::AssertFailed() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:419]
UE4Editor-Engine.dll!UEdGraphPin::SerializePin() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\edgraph\edgraphpin.cpp:1841]
UE4Editor-Engine.dll!UEdGraphPin::SerializePinArray() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\edgraph\edgraphpin.cpp:1786]
UE4Editor-Engine.dll!UEdGraphPin::Serialize() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\edgraph\edgraphpin.cpp:1600]
UE4Editor-Engine.dll!UEdGraphPin::SerializePin() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\edgraph\edgraphpin.cpp:1961]
UE4Editor-Engine.dll!UEdGraphPin::SerializePinArray() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\edgraph\edgraphpin.cpp:1786]
UE4Editor-Engine.dll!UEdGraphNode::Serialize() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\edgraph\edgraphnode.cpp:484]
UE4Editor-BlueprintGraph.dll!UK2Node::Serialize() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\blueprintgraph\private\k2node.cpp:116]
UE4Editor-CoreUObject.dll!StaticDuplicateObjectEx() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:2054]
UE4Editor-UnrealEd.dll!FEdGraphUtilities::CloneGraph() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\edgraphutilities.cpp:223]
UE4Editor-UnrealEd.dll!FEdGraphUtilities::CloneAndMergeGraphIn() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\edgraphutilities.cpp:266]
UE4Editor-KismetCompiler.dll!FKismetCompilerContext::MergeUbergraphPagesIn() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompiler.cpp:2795]
UE4Editor-KismetCompiler.dll!FKismetCompilerContext::CreateAndProcessUbergraph() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompiler.cpp:3012]
UE4Editor-KismetCompiler.dll!FKismetCompilerContext::CreateFunctionList() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompiler.cpp:3550]
UE4Editor-KismetCompiler.dll!FKismetCompilerContext::CompileClassLayout() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompiler.cpp:3802]
UE4Editor-KismetCompiler.dll!FKismet2CompilerModule::CompileBlueprintInner() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompilermodule.cpp:132]
UE4Editor-KismetCompiler.dll!FKismet2CompilerModule::CompileBlueprint() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\kismetcompiler\private\kismetcompilermodule.cpp:219]
UE4Editor-UnrealEd.dll!FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\kismet2\blueprinteditorutils.cpp:2096]
UE4Editor-Kismet.dll!FixSubObjectReferencesPostUndoRedo() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\kismet\private\blueprinteditormodule.cpp:166]
UE4Editor-UnrealEd.dll!UEditorEngine::BroadcastPostUndo() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\editorserver.cpp:5045]
UE4Editor-UnrealEd.dll!UEditorEngine::HandleTransactorUndo() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\editorserver.cpp:1186]
UE4Editor-UnrealEd.dll!TBaseUObjectMethodDelegateInstance<0,UEditorEngine,TTypeWrapper<void> __cdecl(FUndoSessionContext,bool)>::Execute() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:597]
UE4Editor-UnrealEd.dll!TBaseUObjectMethodDelegateInstance<0,UEditorEngine,void __cdecl(FUndoSessionContext,bool)>::ExecuteIfSafe() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:657]
UE4Editor-UnrealEd.dll!TBaseMulticastDelegate<void,FUndoSessionContext,bool>::Broadcast() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:937]
UE4Editor-UnrealEd.dll!UTransBuffer::Undo() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\editortransaction.cpp:899]
UE4Editor-Kismet.dll!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,TTypeWrapper<void> __cdecl(void)>::Execute() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:269]
UE4Editor-Kismet.dll!TBaseSPMethodDelegateInstance<0,FBlueprintEditor,0,void __cdecl(void)>::ExecuteIfSafe() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:345]
UE4Editor-Slate.dll!FUICommandList::ConditionalProcessCommandBindings() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:216]
UE4Editor-Slate.dll!FUICommandList::ProcessCommandBindings() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:160]
UE4Editor-UnrealEd.dll!FBaseToolkit::ProcessCommandBindings() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\toolkits\basetoolkit.cpp:74]
UE4Editor-UnrealEd.dll!SStandaloneAssetEditorToolkitHost::OnKeyDown() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\toolkits\sstandaloneasseteditortoolkithost.cpp:324]
UE4Editor-Slate.dll!<lambda_2afcd964c763e269e2d1a63f3a72f846>::operator()() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5011]
UE4Editor-Slate.dll!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FKeyEvent,<lambda_2afcd964c763e269e2d1a63f3a72f846> >() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:266]
UE4Editor-Slate.dll!FEventRouter::RouteAlongFocusPath<FEventRouter::FBubblePolicy,<lambda_2afcd964c763e269e2d1a63f3a72f846>,FKeyEvent>() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:247]
UE4Editor-Slate.dll!FSlateApplication::ProcessKeyDownEvent() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5009]
UE4Editor-Slate.dll!FSlateApplication::OnKeyDown() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4921]
UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1561]
UE4Editor-ApplicationCore.dll!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2172]
UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:889]
UE4Editor-ApplicationCore.dll!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:726]
USER32.dll!UnknownFunction []
USER32.dll!UnknownFunction []
UE4Editor-ApplicationCore.dll!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:129]
UE4Editor.exe!FEngineLoop::Tick() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3263]
UE4Editor.exe!GuardedMain() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor.exe!GuardedMainWrapper() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor.exe!WinMain() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:210]
UE4Editor.exe!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253]
kernel32.dll!UnknownFunction []
ntdll.dll!UnknownFunction []
ntdll.dll!UnknownFunction []