message: fix: not removing rows that have NULLs that werent caused by an error
diff: @@ -1807,7 +1807,12 @@ void BufferedCSVReader::Flush(DataChunk &insert_chunk) {
  for (idx_t row_idx = 0; row_idx < parse_chunk.size(); row_idx++) {
  bool failed = false;
  for (idx_t column_idx = 0; column_idx < sql_types.size(); column_idx++) {
  - if (insert_chunk.data[column_idx].GetValue(row_idx).IsNull()) {
  +
  + auto& inserted_column = insert_chunk.data[column_idx];
  + auto& parsed_column = parse_chunk.data[column_idx];
  +
  + bool was_already_null = FlatVector::IsNull(parsed_column, row_idx);
  + if (!was_already_null && FlatVector::IsNull(inserted_column, row_idx)) {
  failed = true;
  break;
  }
  