error:
       … while evaluating a branch condition
         at «string»:25:5:
           24|     v:
           25|     if !builtins.isAttrs v || isDrv v then
             |     ^
           26|       v

       … in the left operand of the OR (||) operator
         at «string»:25:28:
           24|     v:
           25|     if !builtins.isAttrs v || isDrv v then
             |                            ^
           26|       v

       … while evaluating definitions from `/nix/store/9iv83r72z5xwgylkwms1qip1ijnr6jqs-source/modules/transposition.nix':

       … while evaluating definitions from `/nix/store/4pi761wvn6m4nlq882j5s2s2bgmx33vf-source/modules/checks/machines.nix, via option perSystem':

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

       … while evaluating definitions from `/nix/store/fv9q2q4cbd2adhnjvlvczjaqzyyw1fdk-source/nixos/modules/system/activation/top-level.nix':

       … while evaluating the option `warnings':

       … while evaluating definitions from `/nix/store/fv9q2q4cbd2adhnjvlvczjaqzyyw1fdk-source/nixos/modules/system/boot/systemd.nix':

       … while evaluating the option `systemd.services.home-manager-cameron.serviceConfig':

       … while evaluating definitions from `/nix/store/xnygwnm7n6j5rnnwb4dcp0i2hlwq5amj-source/nixos':

       … while evaluating the option `home-manager.users.cameron.home.file."/home/cameron/.config/fontconfig/conf.d/10-hm-fonts.conf".source':

       … while evaluating definitions from `/nix/store/xnygwnm7n6j5rnnwb4dcp0i2hlwq5amj-source/modules/misc/xdg':

       … while evaluating the option `home-manager.users.cameron.xdg.configFile."fontconfig/conf.d/10-hm-fonts.conf".source':

       … while evaluating definitions from `/nix/store/xnygwnm7n6j5rnnwb4dcp0i2hlwq5amj-source/modules/misc/fontconfig.nix':

       … while evaluating the option `home-manager.users.cameron.fonts.fontconfig.configFile.fonts.source':

       … while evaluating definitions from `/nix/store/xnygwnm7n6j5rnnwb4dcp0i2hlwq5amj-source/modules/misc/fontconfig.nix':

       … while evaluating the option `home-manager.users.cameron.fonts.fontconfig.configFile.fonts.settings':

       … while evaluating definitions from `/nix/store/xnygwnm7n6j5rnnwb4dcp0i2hlwq5amj-source/modules/misc/fontconfig.nix':

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

       error: Refusing to evaluate package 'tmate-unstable-2022-08-07' in /nix/store/fv9q2q4cbd2adhnjvlvczjaqzyyw1fdk-source/pkgs/by-name/tm/tmate/package.nix:55 because it is marked as insecure

       Known issues:
        - There are no upstream releases since 2019-11.
        - CVE-2018-19387

       You can install it anyway by allowing this package, using the
       following methods:

       a) To temporarily allow all insecure packages, you can use an environment
          variable for a single invocation of the nix tools:

            $ export NIXPKGS_ALLOW_INSECURE=1

          Note: When using `nix shell`, `nix build`, `nix develop`, etc with a flake,
                then pass `--impure` in order to allow use of environment variables.

       b) for `nixos-rebuild` you can add ‘tmate-unstable-2022-08-07’ to
          `nixpkgs.config.permittedInsecurePackages` in the configuration.nix,
          like so:

            {
              nixpkgs.config.permittedInsecurePackages = [
                "tmate-unstable-2022-08-07"
              ];
            }

       c) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
          ‘tmate-unstable-2022-08-07’ to `permittedInsecurePackages` in
          ~/.config/nixpkgs/config.nix, like so:

            {
              permittedInsecurePackages = [
                "tmate-unstable-2022-08-07"
              ];
            }