I used your library to dump entity lumps from tf2 and csgo maps. And as it turns out lumps can be LZMA compressed in tf2 maps.
Is this something you're interested in adding support for?
As per: https://developer.valvesoftware.com/wiki/Source_BSP_File_Format#Versions
Example map would be tf/maps/koth_undergrove_event.bsp
I've implemented the lzma decompression in my tool here: xPaw/EntityLumpDumper@f15372c