The patch is wrong a bit, it should be:
// load logos, if value is "" then skip
logo = getImage(getParameter("al_logo", "appletlogo.png"));
progressbar = getImage(getParameter("al_progressbar", "appletprogress.gif"));
without the check of:
if (getParameter("al_logo").length() > 0) {
and:
if (getParameter("al_progressbar").length() > 0) {
Sorry for that.