message: Fix for parallel scan init: always return operator state
diff: @@ -58,14 +58,14 @@ static unique_ptr<FunctionOperatorData> TableScanParallelInit(ClientContext &con
  auto result = make_unique<TableScanOperatorData>();
  result->column_ids = column_ids;
  result->scan_state.table_filters = filters->table_filters;
  - if (!TableScanParallelStateNext(context, bind_data_p, result.get(), state)) {
  - return nullptr;
  - }
  + TableScanParallelStateNext(context, bind_data_p, result.get(), state);
  return move(result);
  }
  static void TableScanFunc(ClientContext &context, const FunctionData *bind_data_p, FunctionOperatorData *operator_state,
  DataChunk *, DataChunk &output) {
  + D_ASSERT(bind_data_p);
  + D_ASSERT(operator_state);
  auto &bind_data = (TableScanBindData &)*bind_data_p;
  auto &state = (TableScanOperatorData &)*operator_state;
  auto &transaction = Transaction::GetTransaction(context);
  @@ -79,11 +79,13 @@ struct ParallelTableFunctionScanState : public ParallelState {
  };
  idx_t TableScanMaxThreads(ClientContext &context, const FunctionData *bind_data_p) {
  + D_ASSERT(bind_data_p);
  auto &bind_data = (const TableScanBindData &)*bind_data_p;
  return bind_data.table->storage->MaxThreads(context);
  }
  unique_ptr<ParallelState> TableScanInitParallelState(ClientContext &context, const FunctionData *bind_data_p) {
  + D_ASSERT(bind_data_p);
  auto &bind_data = (const TableScanBindData &)*bind_data_p;
  auto result = make_unique<ParallelTableFunctionScanState>();
  bind_data.table->storage->InitializeParallelScan(context, result->state);
  @@ -92,6 +94,9 @@ unique_ptr<ParallelState> TableScanInitParallelState(ClientContext &context, con
  bool TableScanParallelStateNext(ClientContext &context, const FunctionData *bind_data_p,
  FunctionOperatorData *operator_state, ParallelState *parallel_state_p) {
  + D_ASSERT(bind_data_p);
  + D_ASSERT(parallel_state_p);
  + D_ASSERT(operator_state);
  auto &bind_data = (const TableScanBindData &)*bind_data_p;
  auto &parallel_state = (ParallelTableFunctionScanState &)*parallel_state_p;
  auto &state = (TableScanOperatorData &)*operator_state;
  