an error handler for koa, hack ctx.onerror.

different with koa-error:

• we can not just use try catch to handle all errors, steams' and events' errors are directly handle by ctx.onerror, so if we want to handle all errors in one place, the only way i can see is to hack ctx.onerror.
• it is more customizable.

npm install koa-onerror

const fs = require('fs');
const koa = require('koa');
const onerror = require('koa-onerror');

const app = new koa();

onerror(app);

app.use(ctx => {
  // foo();
  ctx.body = fs.createReadStream('not exist');
});

onerror(app, options);

• all: if options.all exist, ignore negotiation
• text: text error handler
• json: json error handler
• html: html error handler
• redirect: if accepct html, can redirect to another error page

check out default handler to write your own handler.

koa-onerror will automatic set err.status as response status code, and err.headers as response headers.

MIT