This is a common crash affecting users in 4.16. Unfortunately they have not provided any additional information
Create a level sequence asset and a level sequence actor that points to it in the level.
Quit - delete the level sequence asset on disk.
Relaunch the editor, select the level sequence actor and click on the Open Level Sequence button in the details panel.
Assertion failed: Asset [File:D:\Build\++UE4+Release-4.16+Compile\Sync\Engine\Source\Editor\UnrealEd\Private\Toolkits\AssetEditorManager.cpp] [Line: 283] UE4Editor_UnrealEd!FAssetEditorManager::OpenEditorForAsset() [asseteditormanager.cpp:283] UE4Editor_DetailCustomizations!FLevelSequenceActorDetails::OnOpenLevelSequenceForActor() [levelsequenceactordetails.cpp:78] UE4Editor_DetailCustomizations!TMemberFunctionCaller<FLevelSequenceActorDetails,FReply() [delegateinstanceinterface.h:165] UE4Editor_DetailCustomizations!UE4Tuple_Private::TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<FLevelSequenceActorDetails,FReply() [tuple.h:497] UE4Editor_DetailCustomizations!TBaseSPMethodDelegateInstance<0,FLevelSequenceActorDetails,0,FReply __cdecl() [delegateinstancesimpl.h:327] UE4Editor_Slate!TBaseDelegate<FReply>::Execute() [delegatesignatureimpl.inl:537] UE4Editor_Slate!SButton::OnMouseButtonUp() [sbutton.cpp:278] UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator() [slateapplication.cpp:5049] UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() [slateapplication.cpp:239] UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [slateapplication.cpp:5038] UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [slateapplication.cpp:5515] UE4Editor_Slate!FSlateApplication::OnMouseUp() [slateapplication.cpp:5495] UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1704] UE4Editor_Core!FWindowsApplication::DeferMessage() [windowsapplication.cpp:2127] UE4Editor_Core!FWindowsApplication::ProcessMessage() [windowsapplication.cpp:867] UE4Editor_Core!FWindowsApplication::AppWndProc() [windowsapplication.cpp:714] user32!UserCallWinProcCheckWow() user32!DispatchMessageWorker() UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [windowsplatformmisc.cpp:1009] UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3058] UE4Editor!GuardedMain() [launch.cpp:166] UE4Editor!GuardedMainWrapper() [launchwindows.cpp:134] UE4Editor!WinMain() [launchwindows.cpp:210] UE4Editor!__scrt_common_main_seh() [exe_common.inl:264] kernel32!BaseThreadInitThunk() ntdll!RtlUserThreadStart()
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-47534 in the post.