Call to undefined function wp_register_feature() in demo agent plugin.

[tolecar]

When I upload and activated wp-feature-api-agent.zip, it breaks the site due the call to undefined function.
Feature API v0.1.6 (wp-feature-api.zip) is installed and activated.

[13-Jun-2025 10:30:17 UTC] PHP Fatal error:  Uncaught Error: Call to undefined function A8C\WpFeatureApiAgent\wp_register_feature() in C:\xampp\htdocs\wp-astro\wp-content\plugins\wp-feature-api-agent\includes\class-wp-feature-register.php:33
Stack trace:
#0 C:\xampp\htdocs\wp-astro\wp-content\plugins\wp-feature-api-agent\includes\class-wp-feature-register.php(22): A8C\WpFeatureApiAgent\WP_Feature_Register->register_features()
#1 C:\xampp\htdocs\wp-astro\wp-content\plugins\wp-feature-api-agent\wp-feature-api-agent.php(43): A8C\WpFeatureApiAgent\WP_Feature_Register->init()
#2 C:\xampp\htdocs\wp-astro\wp-settings.php(545): include_once('C:\\xampp\\htdocs...')
#3 C:\xampp\htdocs\wp-astro\wp-config.php(104): require_once('C:\\xampp\\htdocs...')
#4 C:\xampp\htdocs\wp-astro\wp-load.php(50): require_once('C:\\xampp\\htdocs...')
#5 C:\xampp\htdocs\wp-astro\wp-blog-header.php(13): require_once('C:\\xampp\\htdocs...')
#6 C:\xampp\htdocs\wp-astro\index.php(17): require('C:\\xampp\\htdocs...')
#7 {main}
  thrown in C:\xampp\htdocs\wp-astro\wp-content\plugins\wp-feature-api-agent\includes\class-wp-feature-register.php on line 33

Environment info :

• OS: Win 10
• PHP: 7.4.33 (Xampp)
• WP: 6.8.1