How to handle 'Just “nix::InvalidPath”' error

I’m trying to use a PR from the staging branch (vimPlugins: make usage of luaPackages less confusing · NixOS/nixpkgs@2acce7d) of nixpkgs

This is what I get using my neovim config with nvim-cmp:

fetching e[1mstdenv-linuxe[0m from https://cache.nixos.orge[0me[Kcachix: CppStdException e “\ESC[31;1merror:\ESC[0m path ‘\ESC[35;1m/nix/store/z3i3dsadq645i5966s0xsvjrnnnrw1m4-libidn2-2.3.2\ESC[0m’ is not valid”(Just “nix::InvalidPath”)