[MAINTENANCE] Check whole code with PHPStan and fix reported issues

[stweil]

Description

PHPStan is used in a GitHub action CI test, but this test is currently configured to suppress some error messages.

Reproduction

Run PHPStan without excluding some issues and files:

vendor/bin/phpstan analyze --level=5 Classes

This will report 184 errors. With --level=6 even 692 errors are reported, and higher level further increase the number of reported errors up to 1403 errors with --level=9.

Expected Behavior

Suppressing PHPStan errors in the code (currently used 17 times) or in .github/phpstan.neon should only be used as an intermediate solution.

Ideally PHPStan errors should not be suppressed but analyzed and fixed.

Examples of errors which can be fixed:

• Dubious code in dependency, see Fatal error reported by phpstan ubleipzig/php-iiif-prezi-reader#2.
• The function findOneByParameters is unused and might be removed. Maybe there is more dead code to be removed.
• Calls to undefined functions like findOneByIndexName.

[stweil]

Related: issue #1545.

[sebastian-meyer]

This is a tricky one because we rely on a lot of frameworks (TYPO3, Symfony, Doctrine DBAL, etc.). From my experience it is very hard to get PHPStan (or Psalm) to really cover the whole project including all those frameworks.

For instance, some of your examples are false-positives: findOneByParameters needs to be declared to satisfy interfaces (even if it isn't used), while findOneByIndexName is a totally valid function, because it is handled by a magic method of the Doctrine framework.
There are plugins for PHPStan which cover Doctrine or Symfony and mitigate some of these issues, but there will be more.

Generally, I am a huge fan of static code analyzers and personally work with PHPStan, Psalm and others a lot, but it will be a huge effort to clean up Kitodo.Presentation enough to satisfy higher conformance levels of those tools.