What is error-handling?

Guidelines for handling failures in browser code, server code, APIs, webhooks, and databases. They cover reporting errors, returning suitable responses, logging, recovery, and retries.

It helps implement error boundaries, asynchronous error handling, API status codes, webhook retries, validation errors, and database error logging.

It prevents failures from being hidden or exposed in unsafe ways and gives developers a consistent way to diagnose and recover from them.

error-handling — Cursor rule for Cursor by lacymorrow/paperclip-hub

Install

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.

Clone the repo

git clone --depth 1 https://github.com/lacymorrow/paperclip-hub

Made for: Cursor.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/rules/lacymorrow/paperclip-hub/error-handling/github.svg)](https://agentmods.dev/rules/lacymorrow/paperclip-hub/error-handling)

Your own site

<a href="https://agentmods.dev/rules/lacymorrow/paperclip-hub/error-handling"><img src="https://agentmods.dev/badge/rules/lacymorrow/paperclip-hub/error-handling/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/rules/lacymorrow/paperclip-hub/error-handling"><img src="https://agentmods.dev/badge/rules/lacymorrow/paperclip-hub/error-handling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 516 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00000	$0.00516
Opus 5.5	$0.00000	$0.00206
Sonnet 5.5	$0.00000	$0.00103
Haiku 4.5	$0.00000	$0.00052

Measured yesterday against content hash 09a9a7aff3ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

error-handling 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 yesterday.

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.

.cursor/rules/error-handling.mdc · 110 lines

How it starts

The opening of the file, as written. The whole thing — 110 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Error Handling Best Practices

Client-Side Errors

Use error boundaries
Handle async errors
Provide user feedback
Log errors properly
Implement recovery
Monitor client errors
Document error types

Server-Side Errors

Use proper try/catch
Handle async errors
Implement logging
Return proper status
Monitor server errors
Regular error review
Document procedures

API Errors

Use proper status codes
Return meaningful messages
Handle validation errors
Log API errors
Monitor error rates
Regular error review
Document API errors

Webhook Errors

Return proper HTTP status codes (200 for success, 4xx for client errors)
Implement comprehensive try/catch blocks for webhook processing
Log all webhook processing errors with context (but not sensitive data)
Never expose internal error details in webhook responses
Implement graceful degradation for non-critical webhook failures
Handle signature verification failures appropriately
Implement retry logic for failed webhook processing
Set up alerts for webhook failure patterns
Track webhook success/failure rates
Handle duplicate webhook events gracefully

Database Errors

Handle connection errors
Handle query errors
Implement retries
Log database errors
Monitor error patterns
Regular error review
Document procedures

Validation

Validate all inputs
Handle edge cases
Return clear messages
Log validation errors
Monitor patterns
Regular review
Document rules

Logging

Use proper logging levels
Structure log messages
Include context
Handle sensitive data
Monitor logs
Regular log review
Document patterns

Recovery

Implement fallbacks
Handle graceful degradation
Provide recovery options
Monitor recovery
Test recovery paths
Regular drills
Document procedures

Monitoring

Track error rates
Set up alerts
Monitor patterns
Regular analysis
Take action
Document findings
Share insights

User Experience

Show friendly messages
Provide clear guidance
Handle offline states
Support recovery
Monitor user impact
Regular UX review
Document patterns

Read the full file on GitHub · 110 lines

Changes

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.

yesterday First seen · 110 lines · 516 tokens per session scan A 09a9a7aff3ef

Subscribe to this mod's changes

error-handling is a cursor rule published in the GitHub repository lacymorrow/paperclip-hub (15 stars, last pushed yesterday), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 516 tokens. 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 2026-11-10.

Backend and APIs Debugging ai-agents drizzle-orm nextjs paperclip payload-cms plugin-registry

error-handling next to 6 cursor rules from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
error-handlinglacymorrow/paperclip-hub	Cursor rule	15	yesterday	MIT	A	0	Cursor
fastapi-middlewareWebDevPeterGriffin/The-VibeCode-Bible	Cursor rule	42	7d ago	none	A	91	Cursor
e2e-testingelie222/inbox-zero	Cursor rule	13k	today	none	A	0	Cursor
mcp-debugginggiantswarm/mcp-debug	Cursor rule	38	today	Apache-2.0	A	0	Cursor
1c-exchange-specificsDesko77/cursor-1c-skills	Cursor rule	75	6d ago	MIT	A	0	Cursor
api-designvibestackdev/vibe-stack	Cursor rule	8	yesterday	MIT	A	0	Cursor
RULECacinieP/network-troubleshoot-skill	Cursor rule	8	21d ago	MIT	A	682	Cursor