🚀 Feature Request: Fix static analysis issues reported by PHPStan level 0 (lowest)

[kasparsd]

Describe the problem that needs this feature

In #382 we uncovered a set of issues reported by PHPstan running at lowest strictness level which need to be fixed. Afterwards, we can decide to increase the rule level as desired.

Describe the solution you'd like

Fix the issues reported in tests/phpstan-baseline.neon.

Describe alternatives you've considered

[kasparsd]

The only two remaining issues are listed here https://github.com/fairpm/fair-plugin/blob/1.4.1-RC1/tests/phpstan-baseline.neon#L1-L13 and there is an attempt at fixing some of them in #466.