narrow-bare-rescue
Narrow bare rescue in Elixir so real errors like KeyError and typos propagate instead of being swallowed. Use to audit rescues and refactor error handling.
npx skills add oliver-kriska/claude-elixir-phoenix --skill narrow-bare-rescue --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Narrow Bare Rescue Turn `rescue _ -> fallback` into `rescue _ in [ExceptionType1, ExceptionType2] -> fallback` so programmer bugs propagate while known failure modes stay handled. ## Why this matters Bare rescues (`rescue _ ->`, `rescue e ->` — any form without an `in` clause) swallow **every** exception, including `UndefinedFunctionError` from typos, `KeyError` from misspelled map keys, and `CompileError` from bad HEEx templates. The symptom isn't a stack trace — it's a silent `{:error, :generic}` or a `nil` fallback. Bugs that should surface in tests or error reporters become quiet degradations. The Erlang [Secure Coding Guide](https://www.erlang.org/doc/system/secure_coding.html) makes the same case at the BEAM level — rule **LNG-002** ("Do Not Use `catch`") warns that the legacy catch-all form conflates normal returns, throws, and errors. Bare `rescue` in Elixir is the direct analogue. ## Iron Laws 1. **Never leave `rescue _ ->` or `rescue e ->` without an `in` clause.** Every rescue must list exact exception types. The Credo check enforces this after cleanup lands. 2. **Cover every exception the code path can actually raise.** Narrowing that drops a real exception is a behav
- Why this matters
- Iron Laws
- The core transform
- Workflow
- Step 1 — Find the sites
- Step 2 — Determine the exception set for each bare site
- Step 3 — Apply the narrowing
- Step 4 — Verify
- Scope
- References
grep -rn "^\s*rescue\s*$" <scope> | head -200 grep -rn "defexception" deps/<libname>/lib/ | head -10 mix compile --warnings-as-errors mix format <files_changed> mix test <test_files_for_affected_modules>
What does the narrow-bare-rescue skill do?
Narrow bare rescue in Elixir so real errors like KeyError and typos propagate instead of being swallowed. Use to audit rescues and refactor error handling.
How do I install it?
Run `npx skills add oliver-kriska/claude-elixir-phoenix --skill narrow-bare-rescue --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From oliver-kriska/claude-elixir-phoenix, a repository with 515 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.