codeprobe-error-handling

Standalone Mode

If invoked directly (not via the orchestrator), you must first:

1. Read ../codeprobe/shared-preamble.md (resolve relative to this SKILL.md's location — the sibling codeprobe skill directory — not the user's project) for the output contract, execution modes, and constraints.
2. Load applicable reference files from ../codeprobe/references/ (same resolution) based on the project's tech stack.
3. Default to full mode unless the user specifies otherwise.

Error Handling & Resilience Checker

Domain Scope

This sub-skill detects error handling and resilience issues across these categories:

1. Swallowed Exceptions — Empty catch blocks, catch-and-log-only without rethrow/handle
2. Missing Error Handling — External API calls without try/catch, unhandled promise rejections
3. Error Information — Generic error messages, leaking internals, missing structured responses
4. Retry & Circuit Breaker — No timeout on external calls, no retry for transient failures
5. Validation — Missing input validation, implicit null assumptions, type coercion bugs
6. Transaction Safety — Multi-step DB operations without transactions, missing rollback
7. Logging — No logging on critical paths, missing correlation IDs

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What It Does NOT Flag

• Sensitive data in logs — covered by codeprobe-security (SEC prefix). This sub-skill flags missing logging and structural issues like no correlation IDs, not data leakage.
• Test files — test exception handling follows different patterns and is expected to be simpler.
• Framework-generated exception handlers (e.g., Laravel's Handler.php, Next.js error boundaries that are intentionally minimal) — these are scaffolded defaults, not developer oversights.
• CLI scripts with intentionally simple error handling (print + exit) — command-line tools often use a valid pattern of printing an error and exiting with a non-zero code.
• Catch blocks that deliberately swallow specific known-harmless exceptions with a comment explaining why — if the developer documented the rationale, respect the decision.
• Issues that are primarily security vulnerabilities (e.g., authentication bypasses, injection, data exposure) even if they also have error handling implications — these are covered by codeprobe-security. If both sub-skills flag the same location, the orchestrator will deduplicate and keep the security finding as primary.

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Detection Instructions

Swallowed Exceptions

ID Prefix	What to Detect	How to Detect	Severity
ERR	Empty catch blocks	Search for catch blocks with empty body, only pass, only // ignored, or only a comment. In JS/TS: catch (e) {}. In PHP: catch (\Exception $e) {}. In Python: except: pass or except Exception: pass.	Major
ERR	Catch-log-only without handling	Find catch blocks that only contain a log/print statement but don't rethrow, return an error, or take any recovery action. The exception is swallowed after logging.	Minor
ERR	Overly broad exception catching	catch (\Exception $e), catch (Exception e), bare except: in Python, catch (e) catching all errors. Flag when a more specific exception type should be caught.	Major

Missing Error Handling

ID Prefix	What to Detect	How to Detect	Severity
ERR	External API calls without try/catch	Search for HTTP client calls (Guzzle, axios, fetch, requests, HttpClient), payment SDK calls (Stripe, PayPal), AWS SDK calls, and other external service integrations. Flag when these calls are NOT wrapped in try/catch or .catch().	Major
ERR	Unhandled promise rejections	Search for async functions or promise chains without .catch() or surrounding try/catch. Look for floating promises (async call without await). In Node.js, check for missing unhandledRejection handler.	Major
ERR	File I/O without error handling	file_get_contents, fopen, fs.readFile, open() (Python) without try/catch for IOError/FileNotFoundError.	Minor

Error Information

ID Prefix	What to Detect	How to Detect	Severity
ERR	Generic error messages	API responses returning only "Something went wrong", "Internal server error", or similar without error codes or actionable detail for the client.	Minor
ERR	Leaking internal errors to API consumers	Exception messages, stack traces, SQL errors, or file paths exposed in API JSON/HTML responses. Check error handling middleware configuration.	Major
ERR	Missing structured error responses	API endpoints returning errors without consistent structure (no error code field, no message field, inconsistent formats across endpoints).	Minor

Retry & Circuit Breaker

ID Prefix	What to Detect	How to Detect	Severity
ERR	External service calls without timeout	HTTP client calls without timeout configuration. Guzzle without timeout option, axios without timeout, requests without timeout param, fetch without AbortController.	Major
ERR	No retry for transient failures	External API calls that could fail transiently (HTTP 429, 503, network errors) with no retry mechanism.	Minor
ERR	No circuit breaker for cascading failures	Service-to-service calls in microservice architectures with no circuit breaker or fallback pattern.	Suggestion

Validation

ID Prefix	What to Detect	How to Detect	Severity
ERR	Missing input validation before processing	Functions that accept external input (request params, file contents, API payloads) and use them directly without validation.	Major
ERR	Implicit null assumptions	Accessing properties or calling methods on values that could be null/undefined without null checks. Chaining . access on possibly-null return values.	Minor
ERR	Type coercion bugs	PHP == instead of === for security-sensitive comparisons. JS == instead of ===. Implicit type conversions that could produce unexpected results.	Minor

Transaction Safety

ID Prefix	What to Detect	How to Detect	Severity
ERR	Multi-step DB ops without transactions	Multiple INSERT/UPDATE/DELETE queries in sequence (same method) without DB::transaction(), atomic(), BEGIN/COMMIT, or equivalent. If any step fails, data is left in an inconsistent state.	Critical
ERR	Transaction without proper rollback	Transaction blocks that catch exceptions but don't rollback, or that have code after the transaction that assumes success without checking.	Major

Logging

ID Prefix	What to Detect	How to Detect	Severity
ERR	No logging on critical failure paths	Catch blocks in critical business logic (payment, auth, order processing) that don't include any logging. Failures happen silently.	Major
ERR	Missing correlation/request IDs	Log statements in request-handling code without correlation ID, request ID, or trace ID. Makes debugging distributed issues impossible.	Minor

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ID Prefix & Fix Prompt Examples

All findings use the ERR- prefix, numbered sequentially: ERR-001, ERR-002, etc.

Fix Prompt Examples

• "Wrap the Stripe API call in PaymentService@charge (line 55) in a try/catch for \Stripe\Exception\ApiErrorException. Log the error with context ($orderId, $amount) and throw a domain-specific PaymentFailedException with a user-friendly message."
• "Add DB::transaction() around the order creation flow in OrderService@create (lines 40-65) which currently creates an Order, OrderItems, and Payment record in three separate queries. If any step fails, all should roll back."
• "Replace the empty catch block at app/Services/NotificationService.php:88 with proper error handling: log the exception with notification context, then decide whether to rethrow (critical notification) or swallow with a metric (non-critical)."
• "Add timeout and retry configuration to the HTTP client call at ExternalApiClient.php:30. Use ->timeout(10)->retry(3, 100) for the Guzzle request to handle transient network failures."