Fixed MANTIS-5721 (Editing a download category results in error if not changing rep image)

 * @param  AUTO_LINK $parent_id The parent download category

 * @param  LONG_TEXT $description A description

 * @param  LONG_TEXT $notes Hidden notes pertaining to this download category

 * @param  URLPATH $rep_image The representative image for the category (blank: none)

 * @param  ?URLPATH $rep_image The representative image for the category (blank: none) (null: do not edit)

 * @param  ?SHORT_TEXT $meta_keywords Meta keywords for this resource (null: do not edit)

 * @param  ?LONG_TEXT $meta_description Meta description for this resource (null: do not edit)

 * @param  ?TIME $add_time Add time (null: do not change)

 */

function edit_download_category(int $category_id, string $category, int $parent_id, string $description, string $notes, string $rep_image, ?string $meta_keywords, ?string $meta_description, ?int $add_time = null)

function edit_download_category(int $category_id, string $category, int $parent_id, string $description, string $notes, ?string $rep_image, ?string $meta_keywords, ?string $meta_description, ?int $add_time = null)

{

    $under_category_id = $parent_id;

    while (($under_category_id !== null) && ($under_category_id != INTEGER_MAGIC_NULL)) {