Infinite loading of playground-preview if Service Worker "Update on reload" is checked

Hi,

If I have my dev console open and I have the option "Update on reload" for Service Workers, the playground-preview enters into infinite loading and never shows.

I can reproduce this on https://lit.dev/playground/ .
1. check the option "Update on reload" in Dev Console -> Application -> Service Workers
2. reload the page
3. in the console you can see infinite amount of "Service Worker was updated because "Update on reload" was checked in the DevTools Application panel." 
4. sample preview never loads
5. uncheck "Update on reload"
6. sample loads immediately

Thanks and Regards