Break out of DomainVerificationProxyV1 if info is null

This was found in a presubmit test run, and is probably the result of
a race or an invalid package state. Or even a broken v1 verifier
implementation.

For now, just exit. This failure means the package state is gone, so
continuing verification for it is meaningless.

Bug: 179493004

Test: manual, run v1 verification

Change-Id: Idcfaac95fbd16e7a0981b3d27a2a074c2ede5b1e