Fatal Error when using wp db size

With this plugin enabled, I use ‘wp db size` via the shell and get:

PHP Fatal error: require_once(): Failed opening required '/home/cloudwaysapps.com/abcdefg/public_html/wp-content/plugins/index-wp-mysql-for-speed/code/cli.php' (include_path='.:/usr/share/php') in /home/cloudwaysapps.com/abcdefg/public_html/wp-content/plugins/index-wp-mysql-for-speed/index-wp-mysql-for-speed.php on line 52

I disable the plugin and ‘wp db size` works fine.