Engine crashed during Animation Blueprint compilation with Blend Multi node

Engine crashes if Blend Multi node output is connected to final transition node, and no input is connected to Blend Multi node input parameters.

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1. Open Unreal Engine 4.21
2. Create a new Blueprint project based off of First Person Template
3. In the content folder-> Right click and create a new Animation Blueprint
4. Right click on the Animation Graph, and create a Blend Multi Node.
5. Connect output of "Blend Multi" node to input of "Final Animation Pose" node
6.  Compile and Save

Expected:  A Warning for null or Ignore.

Result: Engine Crashes

LoginId:fefbabe64c2e0c4a43f0439790007b14 EpicAccountId:e5d1a8d997c146e7881b4b49842e4883 Assertion failed: !bProcessed [File[Image Removed]:\Build++UE4+Release-4.19+Compile\Sync\Engine\Source\Runtime\Engine\Private\Animation\AnimNodeBase.cpp] [Line: 146] Initialize already in progress, circular link for AnimInstance [NewAnimBlueprint_C /Engine/Transient.World_0:PersistentLevel.SkeletalMeshActor_0.SkeletalMeshComponent0.NewAnimBlueprint_C_5] Blueprint [AnimBlueprintGeneratedClass /Game/FirstPersonBP/NewAnimBlueprint.NewAnimBlueprint_C] UE4Editor_Core!FDebug::AssertFailed() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:419] UE4Editor_Engine!FPoseLinkBase::Initialize() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\animation\animnodebase.cpp:145] UE4Editor_Engine!FPoseLinkBase::Initialize() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\animation\animnodebase.cpp:162] UE4Editor_AnimGraphRuntime!FAnimNode_MultiWayBlend::Initialize_AnyThread() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\animgraphruntime\private\animnodes\animnode_multiwayblend.cpp:30] UE4Editor_Engine!FPoseLinkBase::Initialize() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\animation\animnodebase.cpp:162] UE4Editor_Engine!FAnimInstanceProxy::InitializeRootNode() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\animation\animinstanceproxy.cpp:234] UE4Editor_Engine!UAnimInstance::InitializeAnimation() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\animation\animinstance.cpp:208] UE4Editor_Engine!USkeletalMeshComponent::InitializeAnimScriptInstance() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\components\skeletalmeshcomponent.cpp:685] UE4Editor_Engine!USkeletalMeshComponent::InitAnim() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\components\skeletalmeshcomponent.cpp:630] UE4Editor_UnrealEd!ReplaceObjectHelper() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:1670] UE4Editor_UnrealEd!FBlueprintCompileReinstancer::ReplaceInstancesOfClass_Inner() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:1958] UE4Editor_UnrealEd!FBlueprintCompileReinstancer::BatchReplaceInstancesOfClass() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\kismet2\kismetreinstanceutilities.cpp:1478] UE4Editor_Kismet!FBlueprintCompilationManagerImpl::FlushReinstancingQueueImpl() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\kismet\private\blueprintcompilationmanager.cpp:1067] UE4Editor_Kismet!FBlueprintCompilationManagerImpl::CompileSynchronouslyImpl() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\kismet\private\blueprintcompilationmanager.cpp:203] UE4Editor_UnrealEd!FKismetEditorUtilities::CompileBlueprint() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\kismet2\kismet2.cpp:741] UE4Editor_Kismet!FBlueprintEditor::Compile() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\kismet\private\blueprinteditor.cpp:3180] UE4Editor_AnimationBlueprintEditor!FAnimationBlueprintEditor::Compile() [d:\build++ue4+release-4.19+compile\sync\engine\source\editor\animationblueprinteditor\private\animationblueprinteditor.cpp:1051] UE4Editor_Kismet!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!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!FUICommandList::ExecuteAction() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:97] UE4Editor_Slate!SToolBarButtonBlock::OnClicked() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\multibox\stoolbarbuttonblock.cpp:300] UE4Editor_Slate!TMemberFunctionCaller<SToolBarButtonBlock,FReply (cdecl SToolBarButtonBlock::)(void) __ptr64>::operator()<>() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegateinstanceinterface.h:156] UE4Editor_Slate!UE4Tuple_Private::TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<SToolBarButtonBlock,FReply (cdecl SToolBarButtonBlock::)(void) __ptr64> >() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\templates\tuple.h:498] UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SToolBarButtonBlock,0,FReply __cdecl(void)>::Execute() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:269] UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:537] UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:282] UE4Editor_Slate!<lambda_1002768c627006711ef2f351a87ec0e7>::operator()() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5440] UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_1002768c627006711ef2f351a87ec0e7> >() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:266] UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5429] UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5927] UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5907] UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1726] UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2172] UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:889] UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:726] user32 user32 UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:129] UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3263] UE4Editor!GuardedMain() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\launch.cpp:166] UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:144] UE4Editor!WinMain() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:223] UE4Editor!_scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253] kernel32 ntdll