Due to some recent changes in the way that we use eslint to check that our coding style linting Mozilla source code in Atom has been broken for a month or two.
I have recently spent some time working on Atom's linter-eslint plugin making it possible to bring all of that linting goodness back to life!
From the root of the project type:
./mach eslint --setup
Install the linter-eslint package v.8.00 or above. Then go to the package settings and enable the following options:
Once done, you should see errors and warnings as shown in the screenshot below: