As I was using my Nexus 6P phone today, the fingerprint sensor was working just fine. However, just a few hours ago today, it stopped working, and I can no longer unlock my device using the fingerprint sensor.
Whenever I put my finger on the sensor, the phone would not respond. When I manually woke up my phone using the power button, it showed me a message "Fingerprint hardware not available".
I tried rebooting my phone, but now the phone doesn't seem to be aware at all that the fingerprint sensor exists. There's no longer even an option to configure it in the device settings.
How can I get the sensor to work again? I have the latest updates installed (Android 8.1 Oreo, with December 2018 patches).