$ nix build .#nixosConfigurations.vm.config.system.build.vm
error:
… while calling the 'derivationStrict' builtin
at /builtin/derivation.nix:9:12: (source not available)
… while evaluating derivation 'nixos-vm'
whose name attribute is located at /nix/store/ikx99aci297hpgys7114fjwyf38iv9qi-source/pkgs/stdenv/generic/make-derivation.nix:348:7
… while evaluating attribute 'buildCommand' of derivation 'nixos-vm'
at /nix/store/ikx99aci297hpgys7114fjwyf38iv9qi-source/pkgs/build-support/trivial-builders/default.nix:87:14:
86| enableParallelBuilding = true;
87| inherit buildCommand name;
| ^
88| passAsFile = [ "buildCommand" ]
(stack trace truncated; use '--show-trace' to show the full trace)
error: attribute 'system' missing
at /nix/store/ikx99aci297hpgys7114fjwyf38iv9qi-source/lib/modules.nix:506:28:
505| builtins.addErrorContext (context name)
506| (args.${name} or config._module.args.${name})
| ^
507| ) (lib.functionArgs f);
