Double slash loading vendor

The widgets.php ist using the following code which loads the js data with a double slash:

    /* Modern browsers will load this smaller bundle */
    wp_enqueue_script( 'friendly-captcha-widget-module',
        plugin_dir_url( __FILE__ ) . '/vendor/widget.module.min.js',

    /* Fallback for (very) old browsers */
    wp_enqueue_script( 'friendly-captcha-widget-fallback',
        plugin_dir_url( __FILE__ ) . '/vendor/widget.polyfilled.min.js',

To correct that you need to delete the Slash / before loading vendor. The code must look like this to be correct:

vendor/widget.module.min.js

and like this 

vendor/widget.polyfilled.min.js