Rollup: Throw on Warning

[gauntface]

I've been using Rollup in a project that is using Lerna to manage package dependencies.

The flow of this set up is:

1. Call lerna bootstrap
2. Lerna will run npm run prepublish in each package as well as npm link
3. In the npm run prepublish step I have a rollup call: "prepublish": "rollup -c"

What I noticed is that warnings are swallowed by Lerna and actually resulted in a bad build, is there anyway to throw on a warning with the CLI?

[Rich-Harris]

yep — you can use a custom onwarn handler for that:

// rollup.config.js
export default {
  // ...
  onwarn: warning => {
    throw new Error(warning.message);
  }
};