Can't export BSP Convert maps to JSON

[Panzerhandschuh]

BSP Convert maps contain a custom game lump for storing primitive vertex texture info data. When attempting to export this to json, I get the following exception: System.ArgumentException: 'The value '1886221417' is not a valid value for the enum 'GameLumpType'.'

I uploaded a few maps that you can use to reproduce the issue here: https://teamstorage.momentum-mod.org/s/yjpg9kCNdC4N9tc