[BUGFIX] Catch exceptions while dumping a file

While dumping a file in the frontend no exceptions are
caught. When a exception happens a 500 HTTP status is thrown.

Catch all exceptions to return the correct 404 HTTP status.

Releases: master,7.6,6.2
Resolves: #76153
Change-Id: Ice7097b6a41432ec580f99185d352307c5f55394
Reviewed-on: https://review.typo3.org/48080


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Frans Saris <franssaris@gmail.com>
Tested-by: Frans Saris <franssaris@gmail.com>