4.0.2 gives white screen of death about meta-box HOT 12 CLOSED

if ( class_exists( 'RW_Meta_Box' ) ) {
    foreach ( $meta_boxes as $meta_box ) {
        new RW_Meta_Box( $meta_box );
    }
}

/********************* META BOXES DEFINITION ***********************/

/**
 * Prefix of meta keys (optional)
 * Wse underscore (_) at the beginning to make keys hidden
 * You also can make prefix empty to disable it
 */
$prefix = 'sl_';

$meta_boxes = array( );

// Events (posts) meta box
$meta_boxes[] = array(
    'id' => 'events',                   // Meta box id, unique per meta box
    'title' => 'Event Details',    // Meta box title
    'pages' => array( 'post' ),         // Post types, accept custom post types as well, default is array('post'); optional
    'context' => 'normal',                // Where the meta box appear: normal (default), advanced, side; optional
    'priority' => 'high',                 // Order of meta box: high (default), low; optional
    'fields' => array(                    // List of meta fields
        array(
            'name' => 'Subtitle',          // Field name
            'id' => $prefix . 'subtitle',      // Field id, i.e. the meta key
            'type' => 'long_text',               // Field type: text box
            'desc' => 'Some events need to have a subtitle, you can fill that in here. You can leave it empty if this event does not need or have a subtitle.'
        ),
        array(
            'name' => 'Event Date',
            'id' => $prefix . 'date',
            'type' => 'date',               // File type: date
            'format' => 'DD MM d, yy',          // Date format, default yy-mm-dd. Optional. See: http://goo.gl/po8vf
            'desc' => 'Format is DD, MM d, yy, for example: Sunday December 25, 2011
If more than one day, leave this open and see Event Period.'
        ),
        array(
            'name' => 'Event Period',          // Field name
            'id' => $prefix . 'period',      // Field id, i.e. the meta key
            'type' => 'long_text',               // Field type: long text field
            'desc' => 'Example 1: Whole month of October 2011
Example 2: Every Tuesday in January 2012
Example 3: Monday, March 5, 2012 - Sunday, March 18, 2012
Only fill in if the event spans a period of more than one day.'
        ),
        array(
            'name' => 'Event Time',
            'id' => $prefix . 'eventtime',
            'type' => 'text',                // Field type: text field
            'desc' => 'Example 1: 6:30-10:30pm
Example 2: 11am-2pm
Example 3 (for Event Period): Every night 6:30pm till late.'
        )
    )
);

/**
 * Register meta boxes
 * Make sure there's no errors when the plugin is deactivated or during upgrade
 */
if ( class_exists( 'RW_Meta_Box' ) ) {
    foreach ( $meta_boxes as $meta_box ) {
        new RW_Meta_Box( $meta_box );
    }
}

// Customization on metaboxes script to make standard textbox a little bit longer
if ( !class_exists( 'RWMB_Long_Text_Field' ) ) {

    class RWMB_Long_Text_Field {

        /**
         * Get field end HTML
         * @param $html
         * @param $meta
         * @param $field
         * @return string
         */
        static function html( $html, $meta, $field ) {
            return "";
        }
    }
}