https://github.com/koajs/onerror/blob/master/index.js#L50

if emit error to app.error event listenter, error will both handled by ctx.onerror and app.on('error');

Is that redundant??

模块抛出这样的异常，如下图。

code

const onerror = require('koa-onerror')
const app = new Koa()

onerror(app, {
  accepts: 'json',
})

.... occurred an error.

Your code print out this message

(node:25492) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): TypeError: options.accepts.call is not a function
(node:25492) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

• How to set up JSON for response error messages when my node program has an error?
• I think your document add some code and comment for this situation. If you reply to my issue, I will send P.R.
• I saw this link( https://github.com/koajs/onerror/blob/master/index.js#L38), so what should I do? What do you want to me? please, more tell me some guide

koajs/error#18

onerror(app, options) <--- how to set this options to json?

Is it possible to support async render like koa-views for koa2?

looking to use this in koa@next - or a better alternative?

when on error,the default return message is html format, how to configure return json format. Thanks a lot!!

Notice https://github.com/koajs/onerror/blob/master/index.js#L35

I'm using server slide render with koa, what means Error will be thrown from a bundler file, then the Error instance is not an instance of node Error.

Then what if I just throw {status: 404}, follow the code it will be transformed to non-error thrown: [Object object], so there will be no way to get the original error message!

Should we just delete this line of code or find another way?

Test:

it('should 404 error ok', function (done) {
  var app = koa();
  app.on('error', function () {});
  onerror(app);

  request(app.callback())
  .get('/404')
  .set('Accept', 'text/html')
  .expect(/<p>Looks like something broke!<\/p>/, done);
});

the reason is: https://github.com/koajs/koa/blob/master/lib/application.js#L130

I've just come into contact with koa related technologies, but the instructions in readme seem a little simple. I don't know how to use onerror to customize my own things. Can you explain it

When errror happens, i want response json not render html page.

If any of the project maintainers have time, can you create a @types/koa-error repository, it would be a great help to ts project, if the maintainers don't have time I can help create it too.

I try to return the common's format on error ,but the json of options is disabled