message: JumpToLast: should not call Prev() if iter->isValid() == false
diff: @@ -1489,15 +1489,11 @@ OP_NAMESPACE_BEGIN
  {
  m_rocks_iter->SeekToLast();
  }
  - if (m_rocks_iter->Valid())
  - {
  -
  - if (!Valid())
  + else
  {
  Prev();
  }
  }
  - }
  else
  {
  m_rocks_iter->SeekToLast();
  