Crash when Listen Server Attempts ServerTravel in Play in New Editor Window

JamesG: New callstack on UDN thread points to UNetDriver::TickFlush

Editor crashes if a listen server attempts to use the console command ServerTravel while in Play in a New Editor Window.

CrashReporter: [Link Removed]

Frequency: 2/2

Reproduction steps copies from UDN:

1. Download and open attached .zip file
2. Set the number of player to 2 (no dedicated server)
3. Set play to New Editor Window instead of Selected Viewport
4. Start the game
5. On the listen server window, bring up the console and execute console command ServerTravel ThirdPersonExampleMap2

Results:

Editor freezes and crashes

Expected:

Server opens map ThirdPersonExampleMap2

Unknown exception - code 00000001 (first/second chance not available)

"Assertion failed: IsValidIndex(Index) && ChunkIndex < NumChunks && Index < MaxTotalElements [File[Image Removed]:\BuildFarm\buildmachine_++depot+UE4-Releases+4.8\Engine\Source\Runtime\Co

KERNELBASE
UE4Editor_Core!FOutputDeviceWindowsError::Serialize() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\private\windows\windowsplatformoutputdevices.cpp:95]
UE4Editor_Core!FOutputDevice::Logf__VA() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\private\misc\outputdevice.cpp:144]
UE4Editor_Core!FDebug::AssertFailed() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\private\misc\outputdevice.cpp:360]
UE4Editor_Core!TStaticIndirectArrayThreadSafeRead<FNameEntry,2097152,16384>::GetItemPtr() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\public\uobject\nametypes.h:312]
UE4Editor_Core!TStaticIndirectArrayThreadSafeRead<FNameEntry,2097152,16384>::operator[]() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\public\uobject\nametypes.h:352]
UE4Editor_Core!FName::ToString() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\private\uobject\unrealnames.cpp:724]
UE4Editor_Core!FName::ToString() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\private\uobject\unrealnames.cpp:718]
UE4Editor_CoreUObject!UObjectBaseUtility::GetName() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\coreuobject\public\uobject\uobjectbaseutility.h:199]
UE4Editor_Engine!FSeamlessTravelHandler::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\world.cpp:4592]
UE4Editor_Engine!UEngine::TickWorldTravel() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\unrealengine.cpp:8480]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\editor\unrealed\private\editorengine.cpp:1277]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\editor\unrealed\private\unrealedengine.cpp:366]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launchengineloop.cpp:2355]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]