How to let Karma skip a browser if not installed

I have a karma.config.js file in a repo that lists different browsers that karma needs to run test on. If I run the test on ubuntu which doesn't have safari install and karma will complain

No binary for Safari browser on your platform. Please set "SAFARI_BIN" env variable. 

How do I configure Karma to automatically skip the browser without giving error if a browser is not installed. I don't want everyone who download the repo to edit the config file.