Require using Error objects as Promise rejection reasons (prefer-promise-reject-errors)

[feross]

This rule aims to ensure that Promises are only rejected with Error objects.

It is considered good practice to only pass instances of the built-in Error object to the reject() function for user-defined errors in Promises. Error objects automatically store a stack trace, which can be used to debug an error by determining where it came from. If a Promise is rejected with a non-Error value, it can be difficult to determine where the rejection occurred.

http://eslint.org/docs/rules/prefer-promise-reject-errors

Rule:

prefer-promise-reject-errors: "error"

[feross]

This will be part of standard v9. Only one repo was affected, and it contained code like this:

if (typeof travisConfig.node_js === 'undefined') {
  logger.error('node_js field not found in travis configuration')
  return Promise.reject()
}

Rejected promises should contain reasons, or they are very difficult to debug. That line should be:

return Promise.reject(new Error('node_js field not found in travis configuration'))