The mutex (required by TestBlockValidity) must be held after creating
the block, until TestBlockValidity is called. Otherwise, it is possible
that the chain advances in the meantime and leads to a crash in
TestBlockValidity:
Assertion failed: pindexPrev && pindexPrev == chainstate.m_chain.Tip() (validation.cpp: TestBlockValidity: 4338)
The diff can be reviewed with the git options
--ignore-all-space --function-context
Github-Pull: 31563
Rebased-From: fa62c8b1f0