NixOS installation

Hey,

I’m trying to install Ossia-Score in NixOS (nixos-version 24.05.1135.9b5328b7f761 (Uakari)) using Home-Manager. My config file looks like this:

{ config, pkgs, lib, ... }:

let
  pkgsUnstable = import <nixpkgs-unstable> {};
in
{
  // ...
  home.packages = with pkgs; [
    // ...
    pkgsUnstable.ossia-score
  ];
}

When I run home-manager switch I get this error:

error:
       … while calling the 'derivationStrict' builtin

         at /builtin/derivation.nix:9:12: (source not available)

       … while evaluating derivation 'home-manager-generation'
         whose name attribute is located at /nix/store/ypdqfzw041rprrlzckic9lmhp9navbiz-nixos-24.05/nixos/pkgs/stdenv/generic/make-derivation.nix:331:7

       … while evaluating attribute 'buildCommand' of derivation 'home-manager-generation'

         at /nix/store/ypdqfzw041rprrlzckic9lmhp9navbiz-nixos-24.05/nixos/pkgs/build-support/trivial-builders/default.nix:68:16:

           67|         enableParallelBuilding = true;
           68|         inherit buildCommand name;
             |                ^
           69|         passAsFile = [ "buildCommand" ]

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: attribute 'ossia-score' missing

       at /home/rog/.config/home-manager/home.nix:80:5:

           79|     # pkgsUnstable.ossia-score
           80|     pkgsUnstable.ossia-score
             |     ^
           81|     patchelf

I have no clue how to fix this, as I also have installed Godot’s lastest version from the unstable packages using pkgsUnstable.godot_4 and it all went well. Any pointers? They would be very much appreciated.

Trying with nix-shell also fails:

error:
       … while calling the 'derivationStrict' builtin

         at /builtin/derivation.nix:9:12: (source not available)

       … while evaluating derivation 'shell'
         whose name attribute is located at /nix/store/ypdqfzw041rprrlzckic9lmhp9navbiz-nixos-24.05/nixos/pkgs/stdenv/generic/make-derivation.nix:331:7

       … while evaluating attribute 'buildInputs' of derivation 'shell'

         at /nix/store/ypdqfzw041rprrlzckic9lmhp9navbiz-nixos-24.05/nixos/pkgs/stdenv/generic/make-derivation.nix:378:7:

          377|       depsHostHost                = elemAt (elemAt dependencies 1) 0;
          378|       buildInputs                 = elemAt (elemAt dependencies 1) 1;
             |       ^
          379|       depsTargetTarget            = elemAt (elemAt dependencies 2) 0;

       error: undefined variable 'ossia-score'

       at «string»:1:107:

            1| {...}@args: with import <nixpkgs> args; (pkgs.runCommandCC or pkgs.runCommand) "shell" { buildInputs = [ (ossia-score) ]; } ""
             |