> nix-shell -p nix-info --run nix-info
system: "x86_64-darwin", multi-user?: yes, version: nix-env (Nix) 2.0.4, channels(lev): "", channels(root): "nixpkgs-18.09pre142355.41cdec2e513", nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixpkgs

> nix-channel --add https://nix.dapphub.com/pkgs/dapphub

> nix-channel --update
unpacking channels...

> nix-env -qa
error: cannot import '/nix/store/lh2mmdwn7xxhiq88zhdva98nyv4v3j7z-source', since path '/nix/store/vzgrkkajvddaq03iafgycvyd1jriszzy-source.drv' is not valid, at /nix/store/n5kfq7prl58q0w6fac1bn25bx6vlhlcs-dapphub/dapphub/nixpkgs/lib/customisation.nix:115:50