Error Monitor

Error Monitoring Setup

Detect Framework

!ls package.json requirements.txt go.mod Cargo.toml *.csproj 2>/dev/null !cat package.json 2>/dev/null | grep -E "react|next|express|fastify|koa|nest|vue|angular|svelte" | head -5 !cat requirements.txt pyproject.toml 2>/dev/null | grep -iE "django|flask|fastapi|starlette" 2>/dev/null | head -5

Existing Error Tracking

!grep -r "sentry\|bugsnag\|rollbar\|airbrake\|errortracking\|newrelic" --include="*.json" --include="*.ts" --include="*.js" --include="*.py" -l 2>/dev/null | head -5

Setup Process

Step 1: Choose Provider

Based on the project stack:

• Sentry: Best overall, supports all major languages
• Bugsnag: Good for mobile and frontend
• Custom: For projects that can't use third-party services

Step 2: Framework-Specific Integration

React/Next.js:

• Error Boundary component wrapping the app
• Sentry.init() in entry point
• Source map upload in build step
• Client-side error capturing

Express/Fastify/Koa:

• Error handling middleware (must be last middleware)
• Request context enrichment (user, request ID)
• Unhandled rejection handler

FastAPI/Django/Flask:

• Middleware for request error capture
• Custom exception handlers
• Background task error tracking

Go:

• Panic recovery middleware
• Error wrapping with context
• Goroutine error capture

Step 3: Configuration

Generate configuration file with:

• DSN/API key reference (from environment variable, never hardcoded)
• Environment detection (development, staging, production)
• Release version tracking
• Sample rate configuration
• Sensitive data scrubbing rules (strip passwords, tokens, PII)

Step 4: Custom Error Classes

Generate project-specific error types:

• AppError base class with code, message, context
• ValidationError for input validation failures
• NotFoundError for missing resources
• AuthError for authentication/authorization failures
• ExternalServiceError for third-party failures

Step 5: Alert Configuration

Recommend alert rules:

• Critical: Unhandled exceptions, auth failures, data corruption
• Warning: High error rate, slow responses, degraded service
• Info: New error types, deployment markers

Rules

• NEVER hardcode DSN/API keys — use environment variables
• Always scrub sensitive data before sending to error tracker
• Include contextual data (user ID, request ID, action) with every error
• Set up source maps for frontend (minified code is useless in stack traces)
• Don't track expected errors (404 for invalid URLs, validation errors)