Log to error_log in fatal case

[R0Wi]

Summary

Write a log message via error_log in case we can't regularly write to our logfile. This improves troubleshooting.

Use case

Example:
We forgot to install the php-apcu module but configured it in config.php. This could happen for example when upgrading the PHP version or when not properly reading the manual.

Before:
When trying to access NC, we're presented with a generic error message.

Internal Server Error

The server encountered an internal error and was unable to complete your request.
Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.
More details can be found in the server log.

Neither nextcloud.log nor /var/log/apache2/error.log (or something similar) is written. As an admin we absolutely don't know what's going on (Btw: I only solved this by debugging via XDebug).

After:
There is a log entry in /var/log/apache2/error.log telling us:

[Mon Jan 23 17:57:01.559577 2023] [php:notice] [pid 189438] [client ::1:48076] Error when trying to log exception: Memcache \\OC\\Memcache\\APCu not available for local cache 
#0 /var/www/html/nextcloud/lib/private/Server.php(745): OC\\Memcache\\Factory->__construct()
#1 /var/www/html/nextcloud/lib/private/AppFramework/Utility/SimpleContainer.php(162): OC\\Server->OC\\{closure}()
#2 /var/www/html/nextcloud/3rdparty/pimple/pimple/src/Pimple/Container.php(122): OC\\AppFramework\\Utility\\SimpleContainer->OC\\AppFramework\\Utility\\{closure}()
#3 /var/www/html/nextcloud/lib/private/AppFramework/Utility/SimpleContainer.php(129): Pimple\\Container->offsetGet()
...

This is not formatted nicely but it tells the admin what's the problem and why the NC server instance is down.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included - not needed
• Screenshots before/after for front-end changes - no changes
• Documentation (manuals or wiki) has been updated or is not required - no doc changes
• Backports requested where applicable (ex: critical bugfixes) - non critical

[psyray]

Thanks for this PR it helps me to identify the problem
It was APCu and memcached PHP extensions missing for me

I don't understand why there is a try..catch without log

[R0Wi]

@nickvergessen I think the CI/CD errors are not related to these changes, right? So could we merge this?

[nickvergessen]

I think the CI/CD errors are not related to these changes, right?

I would recommend to rebase, to proof it.

So could we merge this?

No, missing 2 approvals

[szaimen]

Fine by me then but didnt test

[R0Wi]

The only test currently failing is postgres10-php8.0 :

There was 1 failure:
--
115 |  
116 | 1) Test\User\DatabaseTest::testSearch
117 | Failed asserting that actual size 3 matches expected size 2.
118 |  
119 | /drone/src/tests/lib/User/Backend.php:114
120 | /drone/src/tests/lib/User/DatabaseTest.php:125

Would assume this is not related to the current change?

[R0Wi]

Any chance to get this minor change merged, please?

[nickvergessen]

CI fail is known and unrelated.
So rebasing and setting to merge

[szaimen]

CI failure unrelated