Catch invalid links in FE & BE to keep a working
website.

Resolves: #83283
Releases: master, 8.7
Change-Id: Id9e42dc9be896f3777210843c651f9726dc94552
Reviewed-on: https://review.typo3.org/55024


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>