protected function prepare_excerpt_response( $excerpt, $post ) {

		/** This filter is documented in wp-includes/post-template.php */
		$excerpt = apply_filters( 'the_excerpt', $excerpt, $post );

		if ( empty( $excerpt ) ) {
			return '';
		}

		return $excerpt;
	}
}
<br />
<b>Fatal error</b>:  Uncaught Error: Class 'WP_REST_Revisions_Controller' not found in /home/mrfilame/public_html/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php:18
Stack trace:
#0 /home/mrfilame/public_html/wp-settings.php(262): require()
#1 /home/mrfilame/public_html/wp-config.php(96): require_once('/home/mrfilame/...')
#2 /home/mrfilame/public_html/wp-load.php(50): require_once('/home/mrfilame/...')
#3 /home/mrfilame/public_html/wp-blog-header.php(13): require_once('/home/mrfilame/...')
#4 /home/mrfilame/public_html/index.php(17): require('/home/mrfilame/...')
#5 {main}
  thrown in <b>/home/mrfilame/public_html/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php</b> on line <b>18</b><br />