MDL imported from Substance Source with Datasmith causes a crash

MDL downloaded from Substance Source causes a crash.

This is reported on UDN by an Enterprise customer:

https://udn.unrealengine.com/questions/487598/why-would-ue4-is-always-crashing-when-import-mdl-w.html

Create or open an Unreal Studio project in 4.22 preview 4.

Download a MDL file from Substance Source. I used this one:
[Link Removed]

Extract the zipped up MDL file

Make sure you have nVidia MDL Material Exchange installed:
[Link Removed]

Click the import button in Unreal and import the MDL file you downloaded.

It should crash.

LoginId:a361c40e43ec6566c062aca4f61c8d91
EpicAccountId:9d52d2cc1693402aacdfd31c7fba0886

Unhandled exception

UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::MakeFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateFunctionCallInputs()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateFunctionCallInputs()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateFunctionCallInputs()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateFunctionCallInputs()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionTemporary()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateFunctionCallInputs()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionTemporary()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateFunctionCallInputs()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpressionFunctionCall()
UE4Editor_MDLImporter!Generator::FMaterialExpressionFactory::CreateExpression()
UE4Editor_MDLImporter!FMDLMapHandler::Import()
UE4Editor_MDLImporter!Mdl::FMaterialDistiller::DistilMaps()
UE4Editor_MDLImporter!Mdl::FMaterialDistiller::Distil()
UE4Editor_MDLImporter!Mdl::FMaterialDistiller::Distil()
UE4Editor_MDLImporter!FMDLImporter::DistillMaterials()
UE4Editor_MDLImporter!FMDLImporter::ImportMaterials()
UE4Editor_MDLImporter!UMDLImporterFactory::LoadMaterials()
UE4Editor_MDLImporter!UMDLImporterFactory::FactoryCreateFile()
UE4Editor_UnrealEd!UFactory::ImportObject() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\factories\factory.cpp:187]
UE4Editor_AssetTools!UAssetToolsImpl::ImportAssetsInternal() [d:\build\++ue4\sync\engine\source\developer\assettools\private\assettools.cpp:2027]
UE4Editor_AssetTools!UAssetToolsImpl::ImportAssets() [d:\build\++ue4\sync\engine\source\developer\assettools\private\assettools.cpp:1252]
UE4Editor_AssetTools!UAssetToolsImpl::ImportAssetsWithDialog() [d:\build\++ue4\sync\engine\source\developer\assettools\private\assettools.cpp:1085]
UE4Editor_ContentBrowser!SContentBrowser::ImportAsset() [d:\build\++ue4\sync\engine\source\editor\contentbrowser\private\scontentbrowser.cpp:952]
UE4Editor_ContentBrowser!SContentBrowser::HandleImportClicked() [d:\build\++ue4\sync\engine\source\editor\contentbrowser\private\scontentbrowser.cpp:943]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,SContentBrowser,0,FReply __cdecl(void)>::Execute() [d:\build\++ue4\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:279]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:293]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_6c1f6b862bcfb82ea6dcab28fbcc9463> >() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:271]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5589]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:6194]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:6167]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1842]
UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2292]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1522]
UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:772]
user32
user32
UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:130]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3882]
UE4Editor!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:168]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:145]
UE4Editor!WinMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:275]
UE4Editor!__scrt_common_main_seh() [d:\agent\_work\3\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll