No errors are reported in JS

Completion works, but Oni doesn't report errors in JS files for me. Here is an example file and my jsconfig.json:

Should it work in general? I saw the feature in README.md but not listed here (like "error reports" with a "+"): https://github.com/extr0py/oni/wiki/Languages#javascript-and-typescript

EDIT: Some versions ago I saws the error "Unreachable return statement", but this doesn't show up anymore. This was the only error I saw reported by Oni.