Placing a second landscape spline component crashes editor

Placing multiple spline components crashes editor.

Crash Reporter: [Link Removed]

Frequency: 3/3

1. Open Editor
2. Create new landscape
3. Switch to Manage Mode>Edit Splines
4. Ctrl+LMB to place a spline in viewport
5. Repeat step 4 in another location in viewport

msvcr120! <Unknown>
UE4Editor_Landscape! TArray<UMaterialInterface * __ptr64,FDefaultAllocator>::CopyToEmpty<UMaterialInterface * __ptr64,FDefaultAllocator>() array.h:2217
UE4Editor_Landscape! ULandscapeSplineSegment::UpdateSplinePoints() landscapesplines.cpp:2090
UE4Editor_Landscape! ULandscapeSplineControlPoint::UpdateSplinePoints() landscapesplines.cpp:1561
UE4Editor_LandscapeEditor! FLandscapeToolSplines::AddSegment() landscapeedmodesplinetools.cpp:313
UE4Editor_LandscapeEditor! FLandscapeToolSplines::AddControlPoint() landscapeedmodesplinetools.cpp:359
UE4Editor_LandscapeEditor! FLandscapeToolSplines::BeginTool() landscapeedmodesplinetools.cpp:837
UE4Editor_LandscapeEditor! FEdModeLandscape::InputKey() landscapeedmode.cpp:1205
UE4Editor_UnrealEd! FEditorModeTools::InputKey() editormodemanager.cpp:656
UE4Editor_UnrealEd! FEditorViewportClient::InputKey() editorviewportclient.cpp:1955
UE4Editor_UnrealEd! FLevelEditorViewportClient::InputKey() leveleditorviewport.cpp:2428
UE4Editor_Engine! FSceneViewport::OnMouseButtonDown() sceneviewport.cpp:372
UE4Editor_Slate! SViewport::OnMouseButtonDown() sviewport.cpp:160
UE4Editor_Slate! <lambda_2944fcd867c13fce09ac1f6fe9cbe583>::operator() slateapplication.cpp:3971
UE4Editor_Slate! FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FPointerEvent,<lambda_2944fcd867c13fce09ac1f6fe9cbe583> >() slateapplication.cpp:210
UE4Editor_Slate! FSlateApplication::ProcessMouseButtonDownEvent() slateapplication.cpp:3975
UE4Editor_Slate! FSlateApplication::OnMouseDown() slateapplication.cpp:3884
UE4Editor_Core! FWindowsApplication::ProcessDeferredMessage() windowsapplication.cpp:1344
UE4Editor_Core! FWindowsApplication::DeferMessage() windowsapplication.cpp:1711
UE4Editor_Core! FWindowsApplication::ProcessMessage() windowsapplication.cpp:706
UE4Editor_Core! FWindowsApplication::AppWndProc() windowsapplication.cpp:628
user32! <Unknown>
user32! <Unknown>
UE4Editor_Core! FWindowsPlatformMisc::PumpMessages() windowsplatformmisc.cpp:790
UE4Editor! FEngineLoop::Tick() launchengineloop.cpp:2301
UE4Editor! GuardedMain() launch.cpp:142
UE4Editor! GuardedMainWrapper() launchwindows.cpp:126
UE4Editor! WinMain() launchwindows.cpp:249

Landscape Splines in 4.8