Update code to pass PHPStan level 0

Problem/Motivation

There are several issues that a phpstan analysis found with our code.

Steps to reproduce

Run phpstan against the codebase with level 0. For example (with DDEV and assuming some paths):

ddev exec vendor/bin/phpstan analyze web/modules/contrib/config_enforce_devel

Proposed resolution

Resolve the issues flagged by phpstan to pass level 0 analysis.

Remaining tasks

Run phpstan against the latest code
Inventory the issues
Triage/categorize

We may decide to ignore some flags temporarily if refactoring them out is too risky.

User interface changes

n/a

API changes

None expected.

Data model changes

n/a