fix: handle missing 'path' key in dependency resolution

[rejuvenile]

Summary

Registry deps in workspace package dependency lists may lack a path key — they only have source. The extension code in _generate_hub_and_spokes assumed all deps without a bazel_target have a path, causing KeyError when processing workspace packages that include registry dependencies.

Problem

When a workspace Cargo.toml has dependencies on both local path crates and registry crates (from crates.io), cargo metadata output for the workspace package includes both types in its dependencies list. Registry deps only have source (e.g., registry+https://github.com/rust-lang/crates.io-index) but no path key. The current code does:

bazel_target = "//" + paths.join(workspace_package, _normalize_path(dep["path"]).removeprefix(repo_root + "/"))

This crashes with KeyError on registry deps because dep["path"] doesn't exist.

Fix

Check for the path key with dep.get("path") before using it. If the dep has no path, skip it with continue since registry crates are already handled via the crate hub mechanism.

Changes

• rs/extensions.bzl: Guard against missing path key in workspace package dependency iteration

[dzbarsky]

@rejuvenile I'm not sure I understand the scenario you hit, could you possibly add an e2e smoke test to test/ following the existing examples? (codex/claude should be able to do it easily). That will help me understand and prevent future regression :)

[longlho]

#90 fixes the same thing with test I believe

[dzbarsky]

@rejuvenile please let us know if you're still seeing issues after Long's fix!