jyjeanne/error-handling-express
skills/error-handling-express/SKILL.md
To implement a centralized error handling mechanism in Express applications that captures synchronous and asynchronous errors, logs them properly, and sends standardized responses to the client. Use when: When setting up the application structure; When refactoring to remove try/catch boilerplate in controllers; When ensuring consistent API error responses.
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Last scanned: Apr 6, 2026, 11:33 AM29.5s1 file scanned
SKILL.md
- name:
- error-handling-express
- description:
- To implement a centralized error handling mechanism in Express applications that captures synchronous and asynchronous errors, logs them properly, and sends standardized responses to the client. Use when: When setting up the application structure; When refactoring to remove try/catch boilerplate in controllers; When ensuring consistent API error responses.
Purpose
To implement a centralized error handling mechanism in Express applications that captures synchronous and asynchronous errors, logs them properly, and sends standardized responses to the client.
When to Use
- When setting up the application structure.
- When refactoring to remove
try/catchboilerplate in controllers. - When ensuring consistent API error responses.
Procedure
- Create Custom Error Classes: Extend
Error(e.g.,AppError) with properties forstatusCodeandisOperational. - Create Error Middleware: Define a function with signature
(err, req, res, next). - Handle Known Errors:
- Check if
erris an instance ofAppError. - Use
err.statusCodeanderr.message.
- Check if
- Handle Unknown Errors:
- Log the full error stack (for developers/logs).
- Send a generic 500 "Internal Server Error" message to the client (security).
- Async Wrapper: Create a helper function (e.g.,
catchAsync) to wrap async route handlers and automatically pass errors tonext(). - Register Middleware: Place the error handler as the last middleware in
app.js.
Constraints
- Never expose stack traces in production responses.
- Differentiate between operational errors (invalid input) and programming errors (bugs).
- Ensure all async routes are wrapped or use Express 5+ (which handles rejected promises).
Expected Output
A robust error handling infrastructure including custom error classes, an error handling middleware, and an async wrapper utility.
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