Well, it crashes if you don’t have source control enabled, since PackageStates is always empty:
[2016.11.14-19.33.56:799][ 0]LogWindows:Error: Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\Containers/Array.h] [Line: 634]
[2016.11.14-19.33.56:799][ 0]LogWindows:Error: Array index out of bounds: 0 from an array of size 0
...
[2016.11.14-19.33.56:799][ 0]LogWindows:Error: UE4Editor-UnrealEd.dll!UImportAssetsCommandlet::ImportAndSave() [d:\build\++ue4+release-4.14+compile\sync\engine\source\editor\unrealed\private\commandlets\importassetscommandlet.cpp:195]