Manuel

Try this:

1. hide PHP warnings
2. deactivate the plugin
3. open plugin file: /wp-content/plugins/wc-product-bundles/wcpb.php and change line 41 from this:
   wp_register_script( 'wcpb-script', $this->settings['dir'] . "assets/js/wcpb.js", 'jquery', $this->settings['version'] );
   to this:
   wp_register_script( 'wcpb-script', $this->settings['dir'] . "assets/js/wcpb.js", 'jquery', $this->settings['version'], true );
4. reactivate the plugin