Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add mickeyyaya/refactoring-skills --skill error-handling-patternsgit clone --depth 1 https://github.com/mickeyyaya/refactoring-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/mickeyyaya/refactoring-skills/error-handling-patterns)<a href="https://agentmods.dev/skills/mickeyyaya/refactoring-skills/error-handling-patterns"><img src="https://agentmods.dev/badge/skills/mickeyyaya/refactoring-skills/error-handling-patterns.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00074 | $0.03817 |
| Opus 5 | $0.00037 | $0.01909 |
| Sonnet 5 | $0.00015 | $0.00763 |
| Haiku 4.5 | $0.00007 | $0.00382 |
Grade A, and why
error-handling-patterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 428 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Error Handling Patterns for Code Review
Overview
Swallowed exceptions hide production failures, missing retries cause cascading outages, and overly broad catches mask the real problem. Use this guide during code review to catch error handling hazards before they ship.
When to use: Reviewing code that calls external services, databases, file systems, or async operations; evaluating retry/circuit-breaker logic; any code touching user input or third-party data.
Quick Reference
| Pattern | Core Idea | Primary Red Flag |
|---|---|---|
| Result/Either | Return success or error as a value | Ignoring returned error values, missing .ok check |
| Exception Hierarchies | Structured, typed exception tree | Catching base Exception, throwing generic strings |
| Error Propagation | Each layer adds context before forwarding | Swallowing errors, leaking internal details to callers |
| Retry with Backoff | Retry transient failures with increasing delays | No backoff, no retry limit, retrying non-idempotent ops |
| Circuit Breaker | Stop calling a failing service after threshold | No timeout on HTTP calls, no circuit breaker on dependencies |
| Fail-Fast | Validate inputs immediately at boundaries | Deep processing before input validation, late null checks |
| Graceful Degradation | Partial results or fallback when dependency fails | Entire request fails because one optional service is down |
| Error Boundaries | Contain errors to prevent cascade | Unhandled promise rejections, no global error handler |
| Null Object / Optional | Typed absence eliminates null checks | Null returns from methods, unchecked Optional |
| Dead Letter Queue | Route unprocessable messages for later analysis | Silently dropping failed messages |
Patterns in Detail
1. Result/Either Types
Red Flags:
- Returned error values ignored:
result, _ := doSomething()in Go ResultorEitherreturned but.ok/.isOk()never checked- Mixing exceptions and Result types in the same layer
- Unwrapping without checking:
.unwrap()(Rust) panics onErr
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 428 lines · 74 tokens per session scan A 2d238fd45358
error-handling-patterns is a skill published in the GitHub repository mickeyyaya/refactoring-skills (6 stars, last pushed 5mo ago), licensed MIT. It adds 74 tokens to every session and 3,817 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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