Creating feature for the first time #6606

I'm trying to make a feature that highlights // TODO comments and I really can't get it to run :(
The code inside init() is not running (the console.log is not printed) and I have this warning in console

DevTools failed to load source map: Could not load content for chrome-extension://dehmkhkfkicaaafgjnhpmlocdafjedmh/index.js.map: System error: net::ERR_BLOCKED_BY_CLIENT

Here's the code: https://github.com/iGabyTM/refined-github/tree/feature/highlight-todo-comments