Add sanity asserts for return value of `CBlockIndex::GetAncestor()` where appropriate.
In validation.cpp `CheckSequenceLocks`, check the return value of `tip->GetAncestor(maxInputHeight)` stored into `lp->maxInputBlock`. If it ever returns `nullptr` because the ancestor isn't found, it's going to be a bad bug to keep going, since a `LockPoints` object with the `maxInputBlock` member set to `nullptr` signifies no relative lock time.
In the other places, the added asserts would prevent accidental dereferencing of a null pointer which is undefined behavior.
Co-Authored-By: Aurèle Oulès <aurele@oules.com>
Co-Authored-By: danra <danra@users.noreply.github.com>
listsinceblock now checks that returned transactions are not
conflicting with any transactions that are filtered out by
the given blockhash
Co-Authored-By: Michael Chrostowski <michael.chrostowski@gmail.com>
