Error Checking & Validation

Quick Commands

# Check server logs for errors
tail -n 50 ./server.log

# Watch logs in real-time
tail -f ./server.log

# Test homepage
curl -I http://localhost:3000/

# Test specific page
curl -I http://localhost:3000/dashboard

# Test API route
curl http://localhost:3000/api/your-route

# Check status code only
curl -w "%{http_code}" -o /dev/null -s http://localhost:3000/

Validation Workflow

After ANY change (components, API routes, database, auth):

1. Check Logs

tail -n 50 ./server.log

Look for:

• ✗ Compilation errors (TypeScript, syntax)
• ✗ Runtime errors (module not found, undefined)
• ✗ API route errors (500, auth failures)
• ✗ Database connection issues
• ✗ Next.js build warnings

2. Test Pages

# Should return HTTP/1.1 200 OK
curl -I http://localhost:3000/
curl -I http://localhost:3000/dashboard
curl -I http://localhost:3000/[your-page]

3. Test API Routes

# GET request
curl http://localhost:3000/api/users

# POST with data
curl -X POST http://localhost:3000/api/users \
  -H "Content-Type: application/json" \
  -d '{"name":"Test","email":"test@example.com"}'

# With authentication
curl http://localhost:3000/api/protected \
  -H "Authorization: Bearer YOUR_TOKEN"

Common Error Patterns

Error-Specific Checks

UI Components

# Check for TypeScript/import errors
tail -n 50 ./server.log | grep "error"

# Test page loads
curl -I http://localhost:3000/[page-with-component]

API Routes

# Test endpoint returns expected status
curl -w "%{http_code}" -o /dev/null -s http://localhost:3000/api/route

# Test POST/PUT/DELETE
curl -X POST http://localhost:3000/api/route -H "Content-Type: application/json" -d '{}'

Authentication

# Protected route without token (should return 401)
curl -I http://localhost:3000/api/protected

# Protected route with token (should return 200)
curl http://localhost:3000/api/protected -H "Authorization: Bearer TOKEN"

Database

# Check MongoDB connection in logs
tail -n 50 ./server.log | grep -i "mongo"

# Test CRUD operations via API
curl http://localhost:3000/api/resource
curl -X POST http://localhost:3000/api/resource -H "Content-Type: application/json" -d '{"test":"data"}'

Pre-Deployment Checklist

• No errors in server.log
• All pages return 200
• API routes respond correctly
• Auth protection works (401/403 as expected)
• Database queries succeed
• Forms validate properly
• Error boundaries catch errors

When to Use This Skill

• After creating/modifying components
• After adding/updating API routes
• After database schema changes
• After authentication changes
• Before marking tasks complete
• Before committing code
• Before deployment

NEVER complete a task without running these checks.