Ensure checks are enforced in core_read.cpp for all push types

Summary:
As per title

Depends on D1293, Relates to T327

Test Plan: make check

Reviewers: deadalnix, jasonbcox, jimpo, #bitcoin_abc

Reviewed By: deadalnix, #bitcoin_abc

Subscribers: teamcity

Differential Revision: https://reviews.bitcoinabc.org/D1295