[BUGFIX] Check for columns before iterating over those in page module

Check if there are any columns before iterating over those in the
fluid page module.

Resolves: #91497
Releases: master, 10.4
Change-Id: I2157c39f8bc6af00c8b37774f8dfb0c6ec834000
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65808


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Josef Glatz <josefglatz@gmail.com>
Tested-by: Georg Tiefenbrunn <georg.tiefenbrunn@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Josef Glatz <josefglatz@gmail.com>
Reviewed-by: Georg Tiefenbrunn <georg.tiefenbrunn@gmail.com>
Reviewed-by: Claus Due <claus@phpmind.net>
Reviewed-by: Benni Mack <benni@typo3.org>