I've checked this answer: https://stackoverflow.com/a/34834772/13519865
It tells us to remove this line
apply plugin: 'com.google.gms.google-services'
Removing the line as asked completes the build, but I can't use Firebase (ofc!), it caused a new error, which tells me to add the line: https://stackoverflow.com/a/40085096/13519865
So, I'm stuck in a loop here. Related code sample added here https://github.com/Cyberavater/A.Reader