Check crashing

Note this is on macOS if that matters. I attach my [flake.lock.txt](https://github.com/user-attachments/files/16479126/flake.lock.txt) `nix run github:fzakaria/nix-auto-follow -- -c` gives ``` Node cachix has input nixpkgs pointing to nixpkgs_2 which is not the same as crate2nix's nixpkgs which is nixpkgs_3 in the lockfile. Traceback (most recent call last): File "/nix/store/9aqpdql9cwmsvmdd4m33cnxl9nw6z6xc-nix-auto-follow/bin/.auto-follow-wrapped", line 9, in <module> sys.exit(start()) ^^^^^^^ File "/nix/store/9aqpdql9cwmsvmdd4m33cnxl9nw6z6xc-nix-auto-follow/lib/python3.12/site-packages/nix_auto_follow/cli.py", line 189, in start if not check_lock_file(LockFile.from_dict(flake_lock_json)): ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/9aqpdql9cwmsvmdd4m33cnxl9nw6z6xc-nix-auto-follow/lib/python3.12/site-packages/nix_auto_follow/cli.py", line 101, in check_lock_file f"Please add '{key}.url = \"{flake_lock.nodes[ref].get_url()}\"' or '{other_key}.url = \"{flake_lock.nodes[other_ref].get_url()}'" # noqa: E501 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/9aqpdql9cwmsvmdd4m33cnxl9nw6z6xc-nix-auto-follow/lib/python3.12/site-packages/nix_auto_follow/cli.py", line 45, in get_url raise ValueError(f"Unknown type {original['type']}") ValueError: Unknown type indirect ```