No way to get the original *non-error thrown* message

[JounQin]

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?

[JounQin]

How about this:

if (!(err instanceof Error)) {
  const originalError = err
  let errMsg = 'non-error thrown: '
  try {
    errMsg += JSON.stringify(err);
  } catch (e) {
    errMsg += err
  }
  err = new Error(errMsg);
  err.originalError = originalError
  typeof originalError === 'object' && Object.assign(err, originalError)
}

[dead-horse]

The latest version resolved your problem. https://github.com/koajs/onerror/blob/master/index.js#L38