can't manage to enable busted-nlua backend (nixos)

Using lx 29.2 from nixpkgs, I am not sure why I get the following errors (with the code at https://github.com/teto/rikai.nvim/pull/18, the error doesn't appear on CI as I dont run lx yet over there): ``` lx test ✱✱✱ 0 successes / 0 failures / 4 errors / 0 pending : 0.002341 seconds Error → spec/commands_spec.lua @ 6 is_japanese function setup spec/commands_spec.lua:14: attempt to index global 'vim' (a nil value) stack traceback: spec/commands_spec.lua:14: in function <spec/commands_spec.lua:6> ``` I seem to fulfill everything mentioned in lux's --help: I have nlua in test_dependencies, I have the recommended `section` ``` [test] type = "busted-nlua" flags = [ ] # Optional CLI flags to pass to busted ``` and I have a .busted file as well where I tried with and without `lua = "nlua"` ?