message: Issue Fix Combine segfault
  Check that the local sink state actually has rows before trying to merge them.
diff: @@ -411,10 +411,12 @@ void WindowLocalSinkState::Combine(WindowGlobalSinkState &gstate) {
  // OVER()
  if (over_chunk.ColumnCount() == 0) {
  if (gstate.rows) {
  + if (rows) {
  gstate.rows->Merge(*rows);
  gstate.strings->Merge(*strings);
  rows.reset();
  strings.reset();
  + }
  } else {
  gstate.rows = move(rows);
  gstate.strings = move(strings);
  