anchor.diff:      case try_step(Statement, 0) of
           '$done' -> 
               [];
  +        {error, _} = E -> E;
           {row, Row} ->
               [Row | fetchall(Statement)]
       end.  
  
positive.code:     ColumnNames = column_names(Statement),
      case try_step(Statement, 0) of
          '$done' -> ok;
          {row, Row} -> 
              F(ColumnNames, Row),
              foreach_s(F, Statement)
  
negative.code: map_s(F, Statement) when is_function(F, 1) ->
      case try_step(Statement, 0) of
          '$done' -> [];
          {error, _} = E -> F(E);
          {row, Row} -> 
              [F(Row) | map_s(F, Statement)]
      end;
  