[BUGFIX] Check if $conf['tags.'] is array in ContentObjectRenderer

If a html comment is placed in a fluid template at a position, that
gets parsed by lib.parseFunc_RTE and no "tags" configuration exists for
the parsefunc, a php warning is thrown, because it was not checked if
$conf['tags.'] is an actual array.

Resolves: #91172
Related: #39261
Releases: master
Change-Id: Ia51ff78d7dcda6b74e9e4d218b5345f23c04333d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64304


Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Josef Glatz <josefglatz@gmail.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Josef Glatz <josefglatz@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>