Attribute 'loader' missing

[c0deaddict]

First of all, this is a very awesome project! I've been wanting to convert my Pi Kiosk from Debian to NixOS for a while now. With your project it now seems feasible :)

Unfortunately I can't get it to work. I followed the steps in the README but get the following error:

# ./deploy.sh /dev/sda
error: while evaluating the attribute 'buildCommand' of the derivation 'nixiosk-20.09pre-git-aarch64-linux.img-aarch64-unknown-linux-gnu' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/pkgs/stdenv/generic/make-derivation.nix:197:11:
while evaluating the attribute 'sdImage.populateFirmwareCommands' at undefined position:
while evaluating anonymous function at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:84:45, called from undefined position:
while evaluating the attribute 'value' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:383:9:
while evaluating the option `sdImage.populateFirmwareCommands':
while evaluating the attribute 'mergedValue' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:415:5:
while evaluating the attribute 'values' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:409:9:
while evaluating the attribute 'values' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:508:7:
while evaluating anonymous function at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:395:28, called from /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:395:17:
while evaluating definitions from `/home/jos/tmp/nixiosk/boot/raspberrypi-uboot.nix':
while evaluating 'dischargeProperties' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:467:25, called from /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:396:137:
while evaluating the attribute 'value' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/lib/modules.nix:281:44:
while evaluating the attribute 'text' of the derivation 'config.txt' at /nix/store/mgzskdcr5d58vpmsf17hkil4mx2y326l-source/pkgs/build-support/trivial-builders.nix:7:14:
attribute 'loader' missing, at /home/jos/tmp/nixiosk/boot/raspberrypi-uboot.nix:28:8

This error is for raspberryPi3 but the same error pops up for the other models. Don't know if it matters, but i'm running it from NixOS 20.03

This is my config:

{
    "hostName": "zinc",
    "hardware": "raspberryPi3",
    "authorizedKeys": ["ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDLSCZiKxsQBc5uyQU+nxa32pVwQsVEdFEgjONRvo7ZlnVZ7yxW/WypS9zlrNs6rFX6HPzFx0kJO4PMnqeNeW3+Bt0qLi0iGWufdpXRQBe0dGmqSG9zUYkI2SKPhi9YA8nFBX6g43dbrjtcPMKQjogB0WepXqS94gvyGBWAL6UTTqXrzCVXw4/KkRbWVHoa9SE2HX4TXg10LUcL9kJq9cEGPrSGy7PEnK4o1RwrgifM97Ao4Ah9Y8znWWTH6frVklYzYqUL4NlnUOnUn22EDn2W4SIPVa7rZPLRMAvp1A3ZDjZctjUbHooC3VFpdd3A26jfahzsGVcRfXdcyjx8bZzn jos@magnesium"],
    "program": {
        "package": "epiphany",
        "executable": "/bin/epiphany",
        "args": ["https://en.wikipedia.org/"]
    },
    "networks": {
        "xxx": "yyy"
    },
    "locale": {
        "timeZone": "Europe/Amsterdam",
        "regDom": "NL",
        "lang": "en_US.UTF-8"
    }
}