error:
       … in the left operand of the update (//) operator
         at /var/lib/nixbot/worktrees/1120-0e957ee6551a-700fd37b/flake.nix:77:12:
           76|         }
           77|         // lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
             |            ^
           78|           nixos-test = pkgs.callPackage ./nix/test.nix {

       … while evaluating a branch condition
         at «github:NixOS/nixpkgs/35d3407a3816f3b341d8cf1d60abaf2b7b8166ac?narHash=sha256-BoYPdqk6jlKXy%2BDyUzyGV/CtRGfAhk2MmIgBhsemTGI%3D»/lib/attrsets.nix:1482:29:
         1481|   */
         1482|   optionalAttrs = cond: as: if cond then as else { };
             |                             ^
         1483|

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

       error: Nixpkgs 26.11 has dropped support for x86_64-darwin.

       The 26.05 stable branch still supports x86_64-darwin, and will
       receive security fixes until the end of 2026. If you use channels,
       you can switch to 26.05 as follows:

           $ sudo nix-channel --add https://nixos.org/channels/nixpkgs-26.05-darwin nixpkgs
           $ sudo nix-channel --update

       If this doesn’t work, you may need to run:

           # Lack of sudo is deliberate:
           $ nix-channel --remove nixpkgs

       If you use flakes, switch your flake input:

           inputs.nixpkgs = {
             url = "github:NixOS/nixpkgs/nixpkgs-26.05-darwin";
           };

       See the release notes for more information and alternatives:

         https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.11