message: Fix FromProto for LoadIndex
diff: @@ -621,6 +621,10 @@ std::shared_ptr<Block> FromProto(const proto::Block& block) {
  auto stmt = std::make_shared<Store>(pb_stmt.store().from(), pb_stmt.store().into());
  stmts.push_back(ret->stmts.emplace(ret->stmts.end(), std::move(stmt)));
  } break;
  + case proto::Statement::kLoadIndex: {
  + auto stmt = std::make_shared<LoadIndex>(FromProto(pb_stmt.load_index().from()), pb_stmt.load_index().into());
  + stmts.push_back(ret->stmts.emplace(ret->stmts.end(), std::move(stmt)));
  + } break;
  case proto::Statement::kConstant:
  switch (pb_stmt.constant().value_case()) {
  case proto::Constant::kIconst: {
  