message: fix(header): checking the columns length before appending to the results
diff: @@ -205,6 +205,7 @@ class Header extends Base {
  const cols = columns || this.columns || [];
  let nextRow = [];
  + if (cols && cols.length) {
  result.push(cols);
  for (const col of cols) {
  @@ -216,6 +217,7 @@ class Header extends Base {
  if (nextRow.length) {
  result = result.concat(this.tabularColumns(nextRow));
  }
  + }
  return result;
  }
  