Device is not registered with FCM - No expo token given?

Hello all,

I implemented the Expo push service, but some of the devices come back with the following response:

{ status: 'error',
  message: 'The recipient device is not registered with FCM.',
  details:
   { fault: 'developer',
     error: 'DeviceNotRegistered',
     sentAt: 1562917408 },
  __debug: {} }

In the documentation on push notifications the message field includes an ExponentPushToken[xxxxxxxxxxxxxxxxxxxxxx] portion, which I planned to use to remove the offending token from any notification queues.

The above json however has no indication which device and corresponding token is not registered.

How do I know which token caused the issue so I can remove it from receiving notification requests?