Fix BlockTypes field initialization

[SirYwell]

Overview

Fixes #3524

Description

We need to use our init() method there, otherwise things are mixed up. I added a check to detect such problems earlier.

Submitter Checklist

• Make sure you are opening from a topic branch (/feature/fix/docs/ branch (right side)) and not your main branch.
• Ensure that the pull request title represents the desired changelog entry.
• New public fields and methods are annotated with @since TODO.
• I read and followed the contribution guidelines.