This is a new install of VSCode (1.96.2) and FMTK (2.0.5) on Linux.
Factorio was manually installed in a custom folder.
I opened the mods folder and then clicked on "Factorio (unselected)" at the bottom of the screen, as indicated in workspace.md.
I get an error pop-up saying:
Cannot read properties of undefined (reading 'match')
I did not get the option to "Select other version..." as the documentation indicates.
After much exploration, I found that I needed to edit the global settings.json file (~/.config/Code/User/settings.json) and add the following:
"factorio.versions": [
{ "name": "spaceage",
"factorio_version": "2.0.28",
"factorioPath":"${userHome}/games/factorio-spaceage/factorio/bin/x64/factorio"
}
],
After I added that, the error pop-up no longer occurred and I was able to select the version I added or select another installed version.
I would ask that either that the underlying issue causing the exception be fixed or update workspace.md with a workaround.