Description

If you add an LOD while the editor is simulating or playing, the Editor Crashes.

Found in 4.20 CL# 4369336, 4.21 CL# 4753647, 4.22 CL# 5660361, 4.23 CL# 6063286

Steps to Reproduce
  1. Open the Editor
  2. Create a default particle system and open it
  3. Place the particle in level 
  4. Play in Editor and press Shift+F1
  5. Go to the particle and add an LOD

Results:
The editor will crash

Expected:
No Crash

Callstack
Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\JeremyMain\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 611] Array index out of bounds: -378755904 from an array of size 0

UE4Editor_Core!FWindowsErrorOutputDevice::Serialize() [d:\jeremymain\engine\source\runtime\core\private\windows\windowserroroutputdevice.cpp:79]
UE4Editor_Core!FOutputDevice::LogfImpl() [d:\jeremymain\engine\source\runtime\core\private\misc\outputdevice.cpp:71]
UE4Editor_Core!FDebug::AssertFailed() [d:\jeremymain\engine\source\runtime\core\private\misc\assertionmacros.cpp:446]
UE4Editor_Core!FDebug::CheckVerifyFailedImpl() [d:\jeremymain\engine\source\runtime\core\private\misc\assertionmacros.cpp:424]
UE4Editor_Engine!DispatchCheckVerify<void,<lambda_ac839d0d620246989338f24bfe6f099f> >() [d:\jeremymain\engine\source\runtime\core\public\misc\assertionmacros.h:162]
UE4Editor_Engine!FParticleEmitterInstance::SetCurrentLODIndex() [d:\jeremymain\engine\source\runtime\engine\private\particles\particleemitterinstances.cpp:1144]
UE4Editor_Engine!UParticleSystemComponent::SetLODLevel() [d:\jeremymain\engine\source\runtime\engine\private\particles\particlecomponents.cpp:6954]
UE4Editor_Engine!UParticleSystemComponent::ActivateSystem() [d:\jeremymain\engine\source\runtime\engine\private\particles\particlecomponents.cpp:5915]
UE4Editor_Cascade!FCascade::OnRestartInLevel() [d:\jeremymain\engine\source\editor\cascade\private\cascade.cpp:3833]
UE4Editor_Cascade!FCascade::AddLOD() [d:\jeremymain\engine\source\editor\cascade\private\cascade.cpp:3527]
UE4Editor_Cascade!TBaseSPMethodDelegateInstance<0,FCascade,0,void __cdecl(void)>::ExecuteIfSafe() [d:\jeremymain\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:369]
UE4Editor_Slate!FUICommandList::ExecuteAction() [d:\jeremymain\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:99]
UE4Editor_Slate!SToolBarButtonBlock::OnClicked() [d:\jeremymain\engine\source\runtime\slate\private\framework\multibox\stoolbarbuttonblock.cpp:300]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SToolBarButtonBlock,0,FReply __cdecl(void)>::Execute() [d:\jeremymain\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:293]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\jeremymain\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:294]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_6c1f6b862bcfb82ea6dcab28fbcc9463> >() [d:\jeremymain\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:271]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\jeremymain\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5611]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\jeremymain\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:6216]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\jeremymain\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:6189]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [d:\jeremymain\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1843]
UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage() [d:\jeremymain\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2295]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage() [d:\jeremymain\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1523]
UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc() [d:\jeremymain\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:773]
user32
user32
UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [d:\jeremymain\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:122]
UE4Editor!FEngineLoop::Tick() [d:\jeremymain\engine\source\runtime\launch\private\launchengineloop.cpp:3957]
UE4Editor!GuardedMain() [d:\jeremymain\engine\source\runtime\launch\private\launch.cpp:173]
UE4Editor!GuardedMainWrapper() [d:\jeremymain\engine\source\runtime\launch\private\windows\launchwindows.cpp:145]
UE4Editor!WinMain() [d:\jeremymain\engine\source\runtime\launch\private\windows\launchwindows.cpp:275]
UE4Editor!__scrt_common_main_seh() [d:\agent\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll

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Unresolved
ComponentRendering - Cascade
Affects Versions4.204.214.224.23
Target Fix4.23
CreatedApr 29, 2019
UpdatedApr 29, 2019