Invalid argument

Hi there, I seem to be getting this weird error message in the admin section of a custom post when I set up the meta box using your online generator.

Screenshot

Here’s the code:

function venue_get_meta_box( $meta_boxes ) {
	$prefix = 'prefix-';

	$meta_boxes[] = array(
		'id' => 'venue-meta-box',
		'title' => esc_html__( 'Venue', 'wtf-events' ),
		'post_types' => array('wtf-events' ),
		'context' => 'side',
		'priority' => 'default',
		'autosave' => 'false',
		'fields' => array(
			array(
				'id' => $prefix . 'venue',
				'type' => 'text',
				'name' => esc_html__( 'Venue', 'wtf-events' ),
			),
			array(
				'id' => $prefix . 'venue-image',
				'type' => 'image_select',
				'name' => esc_html__( 'Venue Image', 'wtf-events' ),
				'force_delete' => 'false',
				'max_file_uploads' => '1',
			),
			array(
				'id' => $prefix . 'venue-link',
				'type' => 'url',
				'name' => esc_html__( 'Venue Link', 'wtf-events' ),
			),
		),
	);

	return $meta_boxes;
}
add_filter( 'rwmb_meta_boxes', 'venue_get_meta_box' );