"Unexpected end tag : p in Entity" warning in the site editor

[donnapep]

Fixes the following error in the site editor:

PHP Warning:  DOMDocument::loadHTML(): Unexpected end tag : p in Entity, line: 1 in /Users/donnapep/Local Sites/senseitheme/app/public/wp-content/plugins/sensei/includes/blocks/class-sensei-blocks.php on line 225

Proposed Changes

Check if the block is a core/button immediately in the render_callback for the Course Completed Actions block.

Testing Instructions

1. Activate a block theme.
2. Open the site editor
3. Ensure the PHP warning above is not logged.

Pre-Merge Checklist

• PR title and description contain sufficient detail and accurately describe the changes
• Acceptance criteria is met
• Decisions are publicly documented
• Adheres to coding standards (PHP, JavaScript, CSS, HTML)
• All strings are translatable (without concatenation, handles plurals)
• Follows our naming conventions (P6rkRX-4oA-p2)
• Hooks (p6rkRX-1uS-p2) and functions are documented
• New UIs are responsive and use a mobile-first approach
• New UIs match the designs
• Different user privileges (admin, teacher, subscriber) are tested as appropriate
• Legacy courses (course without blocks) are tested
• Code is tested on the minimum supported PHP and WordPress versions
• User interface changes have been tested on the latest versions of Chrome, Firefox and Safari
• "Needs Documentation" label is added if this change requires updates to documentation
• Known issues are created as new GitHub issues

[github-actions]

Test the previous changes of this PR with WordPress Playground.