Before you're connected to the SFU the local participant object will have the empty string as its ID. This changes to your actual ID once you've connected. Apparently I tried to fix this by forcing the local ID to always be the string 'local' but then I just forgot to use it correctly :)
This adds tests for a couple of the less trivial bits of code in CallViewModel. Testing them helped me uncover why focus switches still weren't being smooth! (It was because I was using RxJS's sample operator when I really wanted withLatestFrom.)