fix: do array access fail save for php versions > 8.0

[zoidbergx]

Fix access on DefaultMockup params array fail save for php versions > 8.0

[github-actions]

Review Checklist

• Target branch (10.5 for bug fixes, others 11.x)
• Bug fix: check if files are affected that were moved to a bundle - create a PR there if applicable
• Tests (if it's testable code, there should be a test for it - get help)
• Docs (every functionality needs to be documented, see here)
• Migration incl. install.sql (e.g. if the database schema changes, ...)
• Upgrade notes (deprecations, important information, migration hints, ...)
• Label
• Milestone