trying hydra-github-jobsets-generator

error evaluating .jobsets

in job ‘jobsets’:
error: access to canonical path '/nix/store/57904rflsfh46y7fxi62rzc7sidc9vmq-user-environment' is forbidden in restricted mode

project.json

{
    "enabled": 1,
    "hidden": false,
    "description": "GitHub Pull Request Jobset Generator",
    "nixexprinput": "generator",
    "nixexprpath": "jobset/generate.nix",
    "checkinterval": 300,
    "schedulingshares": 100,
    "enableemail": false,
    "emailoverride": "",
    "keepnr": 3,
    "inputs": {
        "generator_config": {
            "type": "git",
            "value": "https://github.com/spencerjanssen/dotfiles.git hydra-github-jobsets-generator",
            "emailresponsible": false
        },
        "generator": {
            "type": "git",
            "value": "https://github.com/DeterminateSystems/hydra-github-jobsets-generator.git main",
            "emailresponsible": false
        },
        "nixpkgs": {
            "type": "git",
            "value": "https://github.com/NixOS/nixpkgs.git nixos-unstable-small",
            "emailresponsible": false
        },
        "pull_requests": {
            "type": "githubpulls",
            "value": "spencerjanssen dotfiles",
            "emailresponsible": false
        }
    }
}