error-handling-fundamentalslisted

# Error Handling Fundamentals Review > "Errors are not failures — they're information. Handle them like the valuable data they are." ## When to Apply Activate this skill when reviewing: - try/catch blocks - Promise chains (.then/.catch) - API error responses - Form validation - Network request handling - User-facing error messages --- ## Review Checklist ### Error Catching - [ ] **No empty catches**: Is every catch block doing something meaningful? - [ ] **Proper scope**: Are errors caught at the right level? - [ ] **Context added**: Do errors include helpful debugging info? - [ ] **Finally used**: Are cleanup operations in finally blocks? ### User Experience - [ ] **User-friendly messages**: Will users understand the error? - [ ] **No technical details exposed**: Are stack traces hidden from users? - [ ] **Actionable feedback**: Does the error tell users what to do next? - [ ] **Graceful degradation**: Does the app still work partially on error? ### Logging & Debugging - [ ] **Errors logged**: Are errors recorded for debugging? - [ ] **Context in logs**: Do logs include request ID, user ID, etc.? - [ ] **Severity levels**: Are critical errors distinguished from warnings? ### Recovery - [ ] **Retry logic**: Should this operation retry on failure? - [ ] **Fallback values**: Is there a sensible default on error? - [ ] **Loading states**: Is the user informed while retrying? --- ## Common Mistakes (Anti-Patterns) ### 1. The Empty Catch (The Silent Killer) ``` ❌ t