rust-flake fails at (perhaps idiosyncratic) workspace crate

[tbaumann]

I tried to use rust-flake with https://github.com/nearai/ironclaw/

flake.nix
{
  description = "The OpenFang Agent OS";
  inputs = {
    flake-parts.url = "github:hercules-ci/flake-parts";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    rust-flake.url = "github:juspay/rust-flake";
  };
  outputs = inputs @ {flake-parts, ...}:
    flake-parts.lib.mkFlake {inherit inputs;} {
      imports = [
        inputs.rust-flake.flakeModules.default
        inputs.rust-flake.flakeModules.nixpkgs
      ];
      systems = ["x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin"];
      perSystem = {
        config,
        self',
        inputs',
        pkgs,
        system,
        lib,
        ...
      }: {
        #rust-project.src = lib.sources.cleanSource ./.;
        rust-project.defaults.perCrate.crane.args.buildInputs = with pkgs; [pkg-config openssl];
      };
      flake = {
      };
    };
}

With error

# nix flake show
git+file:///home/tilli/git/ironclaw
error:
       … while evaluating the attribute 'optionalValue.value'
         at /nix/store/zdfpzgjrlxmdiiydiv3vqgvbzbg5fkx0-source/lib/modules.nix:1256:5:
         1255|
         1256|     optionalValue = if isDefined then { value = mergedValue; } else { };
             |     ^
         1257|   };

       … while evaluating a branch condition
         at /nix/store/zdfpzgjrlxmdiiydiv3vqgvbzbg5fkx0-source/lib/modules.nix:1256:21:
         1255|
         1256|     optionalValue = if isDefined then { value = mergedValue; } else { };
             |                     ^
         1257|   };

       … while evaluating definitions from `/nix/store/j5qcw5x2dm0jlffwwymp6yav62l3pdqm-source/modules/transposition.nix':

       … while evaluating the option `perSystem.aarch64-darwin.checks':

       … while evaluating definitions from `/nix/store/36d5a62qn8wx8kba49lscz3k6163ir7g-source/nix/modules/flake-module.nix':

       … while evaluating the option `perSystem.aarch64-darwin.rust-project.crates':

       … while evaluating definitions from `/nix/store/36d5a62qn8wx8kba49lscz3k6163ir7g-source/nix/modules/default-crates.nix':

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: path 'qsjk72zid41skqzm64chlvhwf6b2cyna-.' is not a valid store path: name '.' is not valid

I believe something is funny about the members field in Cargo.toml

#File: Cargo.toml
[workspace]
members = ["."]
exclude = [
    "channels-src/discord",
    "channels-src/telegram",
    "channels-src/slack",
    "channels-src/whatsapp",
    "tools-src/github",
    "tools-src/gmail",
    "tools-src/google-calendar",
    "tools-src/google-docs",
    "tools-src/google-drive",
    "tools-src/google-sheets",
    "tools-src/google-slides",
    "tools-src/slack",
    "tools-src/telegram",
]

[package]
name = "ironclaw"
version = "0.14.0"
edition = "2024"
rust-version = "1.92"
description = "Secure personal AI assistant that protects your data and expands its capabilities on the fly"
authors = ["NEAR AI <support@near.ai>"]
license = "MIT OR Apache-2.0"
homepage = "https://github.com/nearai/ironclaw"
repository = "https://github.com/nearai/ironclaw"
[...]

I don't actually know rust and cargo well enough to spot the issue. It usually just works, also with workspaces. Any ideas?