Problem/Motivation
Fix a bunch of errors reported by PHPStan Strict with all rules disabled, i.e, the "miscellaneous" errors before we can consider introducing strict.
Most of the things identified will be easy/sane DX things.
Steps to reproduce
Add checkInternalClassCaseSensitivity: true to the parameters section of core/phpstan.neon.dist and run phpstan.
Remaining tasks
- CI Pass
- Review.
User interface changes
None.
Introduced terminology
None.
API changes
None.
Data model changes
None.
Release notes snippet
Nil.