I had a firestore.rules syntax error as the other user mentioned. I commented out some rules, but forgot to remove the && that preceded the commented out code. Spent forever trying to figure this out with Gemini...I finally googled it and this was the first link 🫠. Such an unspecific error. You would think either the firebase extension would catch it, or the emulator on startup would catch it, or that it would just straight up tell you in the error message there's an issue with your firestore rules ^🙄