guest agent connection lost: nix config build failed: exit=1 error=None output=error: … while evaluating the file '/nix/store/gzd85r7mnq4px1x5w2cflp5kzg7n31ib-etc-spindle-nixos-default.nix': … while evaluating the attribute 'system' at /nix/store/bmwp8va0bazc5v3vybl00nm1p9z9ah56-9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/default.nix:21:3: 20| 21| system = eval.config.system.build.toplevel; | ^ 22| … from call site at /nix/store/bmwp8va0bazc5v3vybl00nm1p9z9ah56-9figz32vbiblaw5x3li1hc8q9qwlwf27-source/nixos/default.nix:21:12: 20| 21| system = eval.config.system.build.toplevel; | ^ …