message: [Chain] Prevent FindFork from crashing when pindex is null (Only should happen on reindexing and initial sync).
diff: @@ -54,6 +54,9 @@ CBlockLocator CChain::GetLocator(const CBlockIndex* pindex) const
  const CBlockIndex* CChain::FindFork(const CBlockIndex* pindex) const
  {
  + if (pindex == nullptr) {
  + return nullptr;
  + }
  if (pindex->nHeight > Height())
  pindex = pindex->GetAncestor(Height());
  while (pindex && !Contains(pindex))
  