Using table theme without header array will give an error when no rows are passed either

Totally untested but this could fix it.

Maybe isset needs to be replaced with "count".
Not sure.

#1: 1183554-header-warning-fix.patch queued for re-testing.

Re-roll of patch from #1

Works fine. Errors are gone and patch applies nicely.

Could we add a test for this?

testbot let's go

Patch looks good, thanks!

Rerolled #8

Currently this issue doesn't need reroll

Tagging per dimaro work.

This doesn't look to be an issue in D8 (see below). Also, the patch in #8 looks to be a patch against D7, changing the issue version because it may still exist there.

Header has an empty check

  $header_columns = 0;
  if (!empty($variables['header'])) {

As well as body and footer

  // Rows and footer have the same structure.
  $sections = array('rows' , 'footer');
  foreach ($sections as $section) {
    if (!empty($variables[$section])) {
      foreach ($variables[$section] as $row_key => $row) {

• recreated the patch with count($header) check instead of isset().
• Setting issue to needs review for the testbot to pick up my version of the patch.

There are tests in #8 that will need to be backported to D7 too.