81cea5d4ee Ensure m_tip_block is never ZERO (Sjors Provoost)
e058544d0e Make m_tip_block an std::optional (Sjors Provoost)
Pull request description:
Suggested in https://github.com/bitcoin/bitcoin/pull/31297#discussion_r1844244309
ACKs for top commit:
fjahr:
re-ACK 81cea5d4ee
tdb3:
code review re ACK 81cea5d4ee
l0rinc:
ACK 81cea5d4ee
Tree-SHA512: 31a75ba29e3d567bab32e4e7925a419d9d7a4d2d85ed1c1012116d8d22adc14d31d5b4ce5f6c499c994188dcd26a01cced05be74f94c892fc90ae17a6783a472