validation: move nChainTx assert down in CheckBlockIndex

There is a designated section meant for the actual consistency
checks, marked by a comment.

src/validation.cpp

@@ -4862,16 +4862,6 @@ void ChainstateManager::CheckBlockIndex()
  CBlockIndex* pindexFirstAssumeValid = nullptr; // Oldest ancestor of pindex which has BLOCK_ASSUMED_VALID
  while (pindex != nullptr) {
  nNodes++;
- // Make sure nChainTx sum is correctly computed.
- unsigned int prev_chain_tx = pindex->pprev ? pindex->pprev->nChainTx : 0;
- assert((pindex->nChainTx == pindex->nTx + prev_chain_tx)
- // Transaction may be completely unset - happens if only the header was accepted but the block hasn't been processed.
- || (pindex->nChainTx == 0 && pindex->nTx == 0)
- // nChainTx may be unset, but nTx set (if a block has been accepted, but one of its predecessors hasn't been processed yet)
- || (pindex->nChainTx == 0 && prev_chain_tx == 0 && pindex->pprev)
- // Transaction counts prior to snapshot are unknown.
- || pindex->IsAssumedValid());
-
  if (pindexFirstAssumeValid == nullptr && pindex->nStatus & BLOCK_ASSUMED_VALID) pindexFirstAssumeValid = pindex;
  if (pindexFirstInvalid == nullptr && pindex->nStatus & BLOCK_FAILED_VALID) pindexFirstInvalid = pindex;
  if (pindexFirstMissing == nullptr && !(pindex->nStatus & BLOCK_HAVE_DATA)) {
@@ -4954,6 +4944,15 @@ void ChainstateManager::CheckBlockIndex()
  // Checks for not-invalid blocks.
  assert((pindex->nStatus & BLOCK_FAILED_MASK) == 0); // The failed mask cannot be set for blocks without invalid parents.
  }
+ // Make sure nChainTx sum is correctly computed.
+ unsigned int prev_chain_tx = pindex->pprev ? pindex->pprev->nChainTx : 0;
+ assert((pindex->nChainTx == pindex->nTx + prev_chain_tx)
+ // Transaction may be completely unset - happens if only the header was accepted but the block hasn't been processed.
+ || (pindex->nChainTx == 0 && pindex->nTx == 0)
+ // nChainTx may be unset, but nTx set (if a block has been accepted, but one of its predecessors hasn't been processed yet)
+ || (pindex->nChainTx == 0 && prev_chain_tx == 0 && pindex->pprev)
+ // Transaction counts prior to snapshot are unknown.
+ || pindex->IsAssumedValid());
  // Chainstate-specific checks on setBlockIndexCandidates
  for (auto c : GetAll()) {
  if (c->m_chain.Tip() == nullptr) continue;