Probleem met toevoegen srcset function op lijn 252

// Class
$class = implode(' ', apply_filters('john_img_class', $class));
if (!empty($class)) {
$class = 'class="' . esc_attr($class) . '"';
}
// Aspect ratio
$ratio = john_sizes_ratio($width, $height);
if (!empty($ratio)) {
$ratio = 'data-aspect-ratio="' . esc_attr($ratio) . '"';
}
// Attributes
$attributes = implode(' ', apply_filters('john_img_attributes', array('id' => 'id="wp-image-' . esc_attr($id) . '"', 'data-id' => 'data-id="' . esc_attr($id) . '"', 'class' => $class, 'ratio' => $ratio, 'schema' => 'itemprop="contentUrl"', 'alt' => 'alt="' . $alt . '"')));
// Return an array with the final width/height so these values can be passed up to the wrapper element for certain CSS styling tricks
return array(apply_filters('john_img', '<img ' . apply_filters('john_src_html', $src) . apply_filters('john_srcset_html', $srcset) . apply_filters('john_sizes_html', $sizes) . apply_filters('john_dimensions', image_hwstring($width, $height), $width, $height) . $attributes . '>'), $width, $height);