argunix: this attribute failed at evaluation time, before any build started.
attribute: nixosConfigurations.roeland

nix-eval-jobs error:
error:
       … while calling the 'derivationStrict' builtin
         at «nix-internal»/derivation-internal.nix:37:12:
           36|
           37|   strict = derivationStrict drvAttrs;
             |            ^
           38|

       … while evaluating derivation 'nixos-system-roeland-26.05.20260611.a037402'
         whose name attribute is located at «github:nixos/nixpkgs/a0374025a863d007d98e3297f6aa46cc3141c2f0?narHash=sha256-9mUW6gNwoN2SWc/l0fW4svPNOulXLl8ijqKyeSOGgJE%3D»/pkgs/stdenv/generic/make-derivation.nix:647:11

       … while evaluating attribute 'buildCommand' of derivation 'nixos-system-roeland-26.05.20260611.a037402'
         at «github:nixos/nixpkgs/a0374025a863d007d98e3297f6aa46cc3141c2f0?narHash=sha256-9mUW6gNwoN2SWc/l0fW4svPNOulXLl8ijqKyeSOGgJE%3D»/nixos/modules/system/activation/top-level.nix:63:7:
           62|       allowSubstitutes = false;
           63|       buildCommand = systemBuilder;
             |       ^
           64|

       … while evaluating the option `environment.etc."nixos-containers/pykms.conf".source':

       … while evaluating definitions from `/nix/store/9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/modules/system/etc/etc.nix':

       … while evaluating the option `environment.etc."nixos-containers/pykms.conf".text':

       … while evaluating definitions from `/nix/store/9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/modules/virtualisation/nixos-containers.nix':

       … while evaluating the option `containers.pykms.path':

       … while evaluating definitions from `/nix/store/9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/modules/virtualisation/nixos-containers.nix':

       … while evaluating the option `containers.pykms.system.build.toplevel':

       … while evaluating definitions from `/nix/store/9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/modules/system/activation/top-level.nix':

       … while evaluating the option `containers.pykms.warnings':

       … while evaluating definitions from `/nix/store/9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/modules/system/boot/systemd.nix':

       … while evaluating the option `containers.pykms.systemd.services.pykms.serviceConfig':

       … while evaluating definitions from `/nix/store/9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/modules/system/boot/systemd.nix':

       … while evaluating the option `containers.pykms.systemd.services.pykms.preStart':

       … while evaluating definitions from `/nix/store/9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/modules/virtualisation/nixos-containers.nix':

       … while evaluating definitions from `/nix/store/1k10gpdq2rn38lnzlg0g64wxi8s46f1s-source/modules/overlays.nix':

       … while evaluating definitions from `/nix/store/ch5n4xdddid5859dy6c4i6lghqyx8016-source/modules/transposition.nix':

       … while evaluating definitions from `/nix/store/1k10gpdq2rn38lnzlg0g64wxi8s46f1s-source/modules/packages/pykms.nix, via option perSystem':

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

       error: attribute 'unstable' missing
       at /var/lib/argunix/work/26/modules/packages/pykms.nix:3:22:
            2|   perSystem = {pkgs, ...}: {
            3|     packages.pykms = pkgs.unstable.pykms;
             |                      ^
            4|   };
       Did you mean notable?