More Phpstan Level 10 Prep - Writers

[oleibman]

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests
• code quality

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

Why this change is needed?

Ongoing maintenance to eventually get to Phpstan Level 10.

[oleibman]

Scrutinizer unable to handle doctype declarations like array{int, int}. 19 such messages suppressed. One method's complexity went from C to D; no concern whatever about this.