message: Add missing LOCK(cs_main)
diff: @@ -732,6 +732,7 @@ void CInstantSendManager::NotifyChainLock(const CBlockIndex* pindex)
  while (pindex && pindex->GetBlockHash() != lastChainLockBlock) {
  CBlock block;
  {
  + LOCK(cs_main);
  if (!ReadBlockFromDisk(block, pindex, Params().GetConsensus())) {
  pindex = pindex->pprev;
  continue;
  