PN Tessellation and Grass Node Crash Engine

Landscape Materials which use the new Grass Output and have Tessellation turned to PNTriangles will crash the engine

Also reproduced in Main Promotable-CL-2550487 &
Releases/4.8/Promoted-CL-2550455

[Link Removed]

1. Open QAGame Editor
2. Create a New Material
3. Add the Grass Output Node
4. Plug in a Constant (1) into the Grass Node
5. In the Material Attirbutes, set Tessellation Method to PN Triangles
6. Compile and Save Material
7. In the Level, Add a Landscape
8. Assign the Created Material to the Landscape

RESULTS: After the Shaders Compile the engine will freeze then crash

EXPECTED: No Crash, Landscape Tessellated and Grass Output Applied

Fatal error: [Link Removed] [Line: 646]
Rendering thread exception:
Assertion failed: (StartIndex + IndexCount) * IndexBuffer->GetStride() <= IndexBuffer->GetSize() [Link Removed] [Line: 1300]
Start 0, Count 98304, Type 16, Buffer Size 49152, Buffer stride 2

KERNELBASE.dll

{0x000007fefcdc940d}

+ 0 bytes
UE4Editor-Core.dll!FOutputDeviceWindowsError::Serialize()

{0x000007fed2ab6cef}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Core.dll!FOutputDevice::Logf__VA()

{0x000007fed2970148}

+ 159 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Core.dll!FDebug::AssertFailed()

{0x000007fed2941252}

+ 65 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-D3D11RHI.dll!FD3D11DynamicRHI::RHIDrawIndexedPrimitive()

{0x000007fed3186aa3}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Renderer.dll!FMeshDrawingPolicy::DrawMesh()

{0x000007fed1b69405}

+ 104 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Landscape.dll!FLandscapeGrassWeightExporter_RenderThread::RenderLandscapeComponentToTexture_RenderThread()

{0x000007fed2314ef0}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Landscape.dll!TGraphTask<`FLandscapeGrassWeightExporter::FLandscapeGrassWeightExporter'::`18'::EURCMacro_FDrawSceneCommand>::ExecuteTask()

{0x000007fed22d4f71}

+ 18 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Core.dll!FTaskThread::ProcessTasks()

{0x000007fed27f5e2e}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Core.dll!FTaskThread::ProcessTasksUntilQuit()

{0x000007fed27f605d}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-RenderCore.dll!RenderingThreadMain()

{0x000007fef3805d2b}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-RenderCore.dll!FRenderingThread::Run()

{0x000007fef380623f}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Core.dll!FRunnableThreadWin::Run()

{0x000007fed2ab5ac8}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
UE4Editor-Core.dll!FRunnableThreadWin::GuardedRun()

{0x000007fed2aa08ed}

+ 8 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\sou
kernel32.dll

{0x0000000076c259ed}

+ 0 bytes
ntdll.dll

{0x0000000076e5c541} + 0 bytes
ntdll.dll {0x0000000076e5c541}

+ 0 bytes