Possibly missing documentation: ob depends on nix-command being on

[hacklschorsch]

I just installed Obelisk (and nix) fresh on a Mac. ob init runs fine, but ob run fails with this not very informative message:

./.obelisk/impl: command not cached, building ...
✔ Built on ./.obelisk/impl [command]
Process exited with code 1; /nix/store/3xsy9ydsc6csyz8lcrbbp9d9d3xq2kjg-nix-2.11.0/bin/nix eval --impure --expr $'(let a = import ./. {}; in toString (a.reflex.nixpkgs.lib.isDerivation a.passthru.staticFilesImpure))' --raw

Digging a bit it seems nix-command has to be turned on in nix.conf

# ~/.config/nix/nix.conf
experimental-features = nix-command

But that's not documented in the install section of the readme IIANM?

[alexfmpe]

this not very informative message:

FWIW --verbose or -v give more details

But that's not documented in the install section of the readme IIANM?

True, and it has bitten people before as it's a sneaky impurity on the nix config: #1010 (comment)