Function createErrorMiddleware

Create an error handling middleware

Creates middleware that catches and handles errors from downstream middleware and the fetch request. Converts non-FejError errors to FejError instances.

Example: Basic error logging

import { createFej, createErrorMiddleware } from 'fej';

const api = createFej();
api.use('error-handler', createErrorMiddleware((error, ctx) => {
  console.error(`Request to ${ctx.request.url} failed:`, error.message);
}));
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Example: Error handling with reporting

api.use('error-handler', createErrorMiddleware(async (error, ctx) => {
  // Log to error tracking service
  await errorTracker.report({
    message: error.message,
    url: ctx.request.url,
    stack: error.stack,
  });

  // Show user-friendly message
  if (ctx.response?.status === 404) {
    console.log('Resource not found');
  }
}));
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