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kumaran-iskumaran-is/claude-code-onboarding/.claude/skills/silent-failure-hunter/SKILL.md

silent-failure-hunter

Skill35 starsChanged 6 months agoMITView on GitHub

Audits error handling for swallowed exceptions, empty catch blocks, unjustified fallbacks, and mock data returns on failure. Use after implementing features with API calls, database operations, or any I/O that can fail. Enforces code-standards.md "No Silent Failures" rule.

3 other projects use a version of this.

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The file

We split this skill into the rules it gives an agent

2 rules. 0 are common, 2 are distinctive, and 0 are very specific to this project.

  • 0

    Common

    Most of the 3 edited versions we read keep these.

  • 2

    Distinctive

    This author's own choices. Worth a look.

  • 0

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    After implementing features with API calls or database operations

    line 25
  2. Distinctive:

    Before merging code that touches external service integrations

    line 27

“Common” is measured: kept by at least 6 in 10 of the 3 edited versions of this file we could read. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Iron Law: An empty catch block is not error handling — it is a lie to the operator. Every catch must log AND rethrow or return an error state.

Silent Failure Hunter

Enforces the "No Silent Failures" rule from code-standards.md — every catch block must log the error AND either rethrow or return an explicit error state. Finds swallowed exceptions, fallbacks that hide failures, and mock data returned on error.

When to Use

  • After implementing features with API calls or database operations
  • Reviewing any code that has try/catch blocks
  • Before merging code that touches external service integrations
  • Proactively after implementing I/O-heavy features

Forbidden Patterns (all languages)

catch (e) { return []; }           // Silent empty return
catch (e) { return MockData.x; }   // Fake data on failure
catch (e) { /* nothing */ }        // Swallowed exception
catch (e) { log.error(e); }        // Log only, no rethrow

Required Pattern

catch (e) {
  logger.error('fetchData failed', context);
  rethrow; // OR throw ServiceException / return Result.failure
}

Stack-Specific Patterns to Grep

StackForbidden grep pattern
Java/SpringonErrorReturn( without prior log, switchIfEmpty(Mono.empty())
NestJScatch.*return null, empty catch blocks
Pythonexcept.*pass, except.*return \[\]
Fluttercatch.*\{\s*\}, on Exception.*return null

Severity Levels

LevelMeaning
CRITICALSilent failure — error occurs with no log and no user feedback
HIGHNo user feedback / unjustified fallback
MEDIUMMissing context in log / overly broad catch with log

Output Format

## Silent Failure Audit: [scope]

### CRITICAL
[file:line] — [description of silent failure]
Hidden errors: [types that could be suppressed]
Fix: [corrected code]

### Summary
- Issues: N (critical: X, high: Y, medium: Z)
- Verdict: PASS / FAIL

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