error:
       … in the right operand of the update (//) operator
         at /var/lib/nixbot/worktrees/255-f8c947e28c5c-8c4d527f/flake.nix:75:34:
           74|         in
           75|         packages // devShells // vmTests);
             |                                  ^
           76|     };

       … while evaluating a branch condition
         at «github:nixos/nixpkgs/3d2613bc58a1f5b7805467a63a825e1d7bc9b7a9?narHash=sha256-4Ztw87nz9iSaxfh/3mqXs4B/YXjx8%2BPnxBRdUi1akYk%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