Don’t push latest Firebase. Use whichever version is packaged with the most recent AngularFire2 in the AF2 changelog.
The problem started happening before I changed anything related to firebase, and then once everything broke, i ran npm update to get the latest firebase version (because I assumed the new release on their end was causing problems with ionic) but that didn’t help
I was getting the same errors and removed them by rolling back firebase from version 4.8.1 to 4.6. Try: npm install --save firstname.lastname@example.org in CLI. Hope this helps