I'm developing a website and noticed while testing that firefox sends requests to "/sw.js" on my local webserver. When starting with a fresh profile folder, this does not happen (and also not with other browsers). So, I thought, this might be one of my extensions, but in Troubleshooting mode, the browser still sends these requests, everytime a site is refreshed. It does not affect performance or anything, I am just afraid that I was somehow hacked as I did not make many settings in firefox. Do you know, how I could further diagnose the problem?