Fullscreen Editor Crash when setting both IndexBuffers to False

When setting both IndexBuffers to False the Editor will crash when attempting to use Fullscreen mode with F11.

1. Open the DefaultEngine.ini file and set the following
   1. r.SupportReversedIndexBuffers=False
   2. r.SupportDepthOnlyIndexBuffers=False
2. Open up the project and press "F11" to Fullscreen the Editor window.

Results: The Editor will crash.

Expected. The Editor to go Fullscreen and remain usable.

Unhandled exception UE4Editor_Engine!FStaticMeshSceneProxy::SetMeshElementGeometrySource() [d:\build\++ue4\sync\engine\source\runtime\engine\private\staticmeshrender.cpp:749] UE4Editor_Engine!FStaticMeshSceneProxy::GetWireframeMeshElement() [d:\build\++ue4\sync\engine\source\runtime\engine\private\staticmeshrender.cpp:561] UE4Editor_Engine!FStaticMeshSceneProxy::GetDynamicMeshElements() [d:\build\++ue4\sync\engine\source\runtime\engine\private\staticmeshrender.cpp:1211] UE4Editor_Renderer!FSceneRenderer::GatherDynamicMeshElements() [d:\build\++ue4\sync\engine\source\runtime\renderer\private\scenevisibility.cpp:2804] UE4Editor_Renderer!FSceneRenderer::ComputeViewVisibility() [d:\build\++ue4\sync\engine\source\runtime\renderer\private\scenevisibility.cpp:3864] UE4Editor_Renderer!FDeferredShadingSceneRenderer::InitViews() [d:\build\++ue4\sync\engine\source\runtime\renderer\private\scenevisibility.cpp:4152] UE4Editor_Renderer!FDeferredShadingSceneRenderer::Render() [d:\build\++ue4\sync\engine\source\runtime\renderer\private\deferredshadingrenderer.cpp:908] UE4Editor_Renderer!RenderViewFamily_RenderThread() [d:\build\++ue4\sync\engine\source\runtime\renderer\private\scenerendering.cpp:3242] UE4Editor_Renderer!TGraphTask<TEnqueueUniqueRenderCommandType<`FRendererModule::BeginRenderingViewFamily'::`27'::FDrawSceneCommandName,<lambda_98974a148448e2faeb6b39d7ee44228d> > >::ExecuteTask() [d:\build\++ue4\sync\engine\source\runtime\core\public\async\taskgraphinterfaces.h:847] UE4Editor_Core!FNamedTaskThread::ProcessTasksNamedThread() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:686] UE4Editor_Core!FNamedTaskThread::ProcessTasksUntilQuit() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:583] UE4Editor_RenderCore!RenderingThreadMain() [d:\build\++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:340] UE4Editor_RenderCore!FRenderingThread::Run() [d:\build\++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:471] UE4Editor_Core!FRunnableThreadWin::Run() [d:\build\++ue4\sync\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:96]