selectMaybeOne = async (tbl, where, selectopts = Object.create(null)) => {
  const rows = await select(tbl, where, { ...selectopts, limit: 1 });
  if (rows.length === 0) return null;
  else return rows[0];
}
Select one record or null if no records
@param {string} tbl - table name
@param {object} where - where object
@param {object} [selectopts = {}] - select options
@returns {Promise<null|object>} - null if no record or first record data