Crash when adding Emitter in parameters in Niagara

[2018.06.07-14.42.46:888][358]LogWindows: Error: [Callstack] 0x00007ffa95363c58 KERNELBASE.dll!UnknownFunction []
[2018.06.07-14.42.46:888][358]LogWindows: Error: [Callstack] 0x00007ffa7f8d6830 UE4Editor-ApplicationCore.dll!FWindowsErrorOutputDevice::Serialize() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\applicationcore\private\windows\windowserroroutputdevice.cpp:65]
[2018.06.07-14.42.46:888][358]LogWindows: Error: [Callstack] 0x00007ffa62cb4efc UE4Editor-Core.dll!FOutputDevice::LogfImpl() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:70]
[2018.06.07-14.42.46:888][358]LogWindows: Error: [Callstack] 0x00007ffa62c44cbb UE4Editor-Core.dll!FDebug::AssertFailed() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:425]
[2018.06.07-14.42.46:888][358]LogWindows: Error: [Callstack] 0x00007ffa463275db UE4Editor-NiagaraEditor.dll!SNiagaraParameterMapView::OnGetParameterMenu() [d:\build\++ue4+release-4.20+compile\sync\engine\plugins\fx\niagara\source\niagaraeditor\private\widgets\sniagaraparametermapview.cpp:479]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa46306abe UE4Editor-NiagaraEditor.dll!TBaseSPMethodDelegateInstance<0,SNiagaraParameterMapView,0,TSharedRef<SWidget,0> __cdecl(void),enum NiagaraParameterMapSectionID::Type>::Execute() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:269]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa6274f617 UE4Editor-Slate.dll!SMenuAnchor::SetIsOpen() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\slate\private\widgets\input\smenuanchor.cpp:307]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa6272fc62 UE4Editor-Slate.dll!SComboButton::OnButtonClicked() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\slate\private\widgets\input\scombobutton.cpp:86]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa62711cdf UE4Editor-Slate.dll!TBaseSPMethodDelegateInstance<0,SComboButton,0,FReply __cdecl(void)>::Execute() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:269]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa627376be UE4Editor-Slate.dll!SButton::OnMouseButtonDown() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:223]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa625281cf UE4Editor-Slate.dll!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FPointerEvent,<lambda_7097b900f0e4be30d80fb18f98c51ea0> >() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:268]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa625bff42 UE4Editor-Slate.dll!FSlateApplication::RoutePointerDownEvent() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5365]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa625a770c UE4Editor-Slate.dll!FSlateApplication::ProcessMouseButtonDownEvent() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5318]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa6259ab1a UE4Editor-Slate.dll!FSlateApplication::OnMouseDown() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5236]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa7f8cd24f UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1744]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa7f8c0250 UE4Editor-ApplicationCore.dll!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2182]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa7f8cf4a5 UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:895]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa7f8bc1e9 UE4Editor-ApplicationCore.dll!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:732]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa96f31c24 USER32.dll!UnknownFunction []
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa96f3156c USER32.dll!UnknownFunction []
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ffa7f8d0626 UE4Editor-ApplicationCore.dll!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:129]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ff74d6354c5 UE4Editor.exe!FEngineLoop::Tick() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3408]
[2018.06.07-14.42.46:889][358]LogWindows: Error: [Callstack] 0x00007ff74d645b3c UE4Editor.exe!GuardedMain() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
[2018.06.07-14.42.46:890][358]LogWindows: Error: [Callstack] 0x00007ff74d645bba UE4Editor.exe!GuardedMainWrapper() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:144]
[2018.06.07-14.42.46:890][358]LogWindows: Error: [Callstack] 0x00007ff74d653d5c UE4Editor.exe!WinMain() [d:\build\++ue4+release-4.20+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:223]
[2018.06.07-14.42.46:890][358]LogWindows: Error: [Callstack] 0x00007ff74d655a5a UE4Editor.exe!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283]
[2018.06.07-14.42.46:890][358]LogWindows: Error: [Callstack] 0x00007ffa98d88364 KERNEL32.DLL!UnknownFunction []
[2018.06.07-14.42.46:890][358]LogWindows: Error: [Callstack] 0x00007ffa98e970b1 ntdll.dll!UnknownFunction []