Nix store output path is empty unless name is specified

[samuela]

As the title says, I have a flake.nix:

{
  inputs = {
    utils.url = "github:numtide/flake-utils";
    naersk.url = "github:nix-community/naersk";
  };

  outputs = { self, naersk, nixpkgs, utils }:
    utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };
        naersk-lib = pkgs.callPackage naersk { };
      in with pkgs; {
        packages.cherami-build = naersk-lib.buildPackage {
          # When `name = "cherami-build";` is commented out,
          #
          #   root@b62e2017d34d:/workspaces/bitbop# ls $(nix build .#cherami-build --json | jq ".[].outputs.out" --raw-output)
          #   root@b62e2017d34d:/workspaces/bitbop#
          #
          # But when uncommented,
          #
          #   root@b62e2017d34d:/workspaces/bitbop# ls $(nb .#cherami-build --json | jq ".[].outputs.out" --raw-output)
          #   bin
          #   root@b62e2017d34d:/workspaces/bitbop#
          #
          name = "cherami-build";
          src = ./cherami;
        };
      });
}

And the output directory is only non-empty when name is specified? Why?

My flake.lock file is available in this gist.