Crash when changing the number of instances in a grouped sprite component at runtime

A crash occurs when you remove a Sprite Instance within a Paper Grouped Sprite component of an Actor BP on Event Begin Play.

I was able to reproduce this crash in the binary releases of 4.11.2 and 4.12.5, as well as Dev-Main CL-3075390.

1. Download and Open the attached project.
2. Press PIE

Outcome Crash occurs

Expected The Sprite Instance is removed on EventBegin Play

UE4Editor_Paper2D!FGroupedSpriteSceneProxy::SetAllBodySetups_RenderThread() groupedspritesceneproxy.cpp:124
UE4Editor_Paper2D!`UPaperGroupedSpriteComponent::CreateAllInstanceBodies'::`14'::EURCMacro_FSendPaperGroupBodySetups::DoTask() papergroupedspritecomponent.cpp:352
UE4Editor_Paper2D!TGraphTask<`UPaperGroupedSpriteComponent::CreateAllInstanceBodies'::`14'::EURCMacro_FSendPaperGroupBodySetups>::ExecuteTask() taskgraphinterfaces.h:999
UE4Editor_Core!FNamedTaskThread::ProcessTasksNamedThread() taskgraph.cpp:932
UE4Editor_Core!FNamedTaskThread::ProcessTasksUntilQuit() taskgraph.cpp:679
UE4Editor_RenderCore!RenderingThreadMain() renderingthread.cpp:319
UE4Editor_RenderCore!FRenderingThread::Run() renderingthread.cpp:440
UE4Editor_Core!FRunnableThreadWin::Run() windowsrunnablethread.cpp:74