… while checking flake output 'packages'

         at /nix/store/p58d2j0ac7zvja5jl14xzbc19fakjxh2-source/lib.nix:39:17:

           38|               {
           39|                 ${key} = (attrs.${key} or { })
             |                 ^
           40|                   // { ${system} = ret.${key}; };

       … while checking the derivation 'packages.aarch64-darwin.default'

         at /nix/store/2gi1wlrjl6n629fc5sbiz5lgl12pclxx-source/flake.nix:77:9:

           76|         # Expose external output packages
           77|         packages.default = multiBuild.package;
             |         ^
           78|

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

       error: unable to find Cargo.lock at /nix/store/ys1hmv2sxbd3a8a68l35k9qgx3nlj25q-source. please ensure one of the following:
       - a Cargo.lock exists at the root of the source directory of the derivation
       - set `cargoVendorDir = vendorCargoDeps { cargoLock = ./some/path/to/Cargo.lock; }`
       - set `cargoVendorDir = vendorCargoDeps { src = ./src/containing/cargo/lock/file; }`
       - set `cargoVendorDir = null` to skip vendoring altogether

 I  ~/g/b/bdk einherjar/nix• 1.6s | 1 ❱ git st
On branch einherjar/nix
Your branch is up to date with 'origin/einherjar/nix'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   flake.lock
        modified:   flake.nix

no changes added to commit (use "git add" and/or "git commit -a")

I  ~/g/b/bdk einherjar/nix• ❱ cat .gitignore
/target
Cargo.lock
/.vscode

*.swp
.idea

# Example persisted files.
*.db