I found this bug with one on my mp3.
i debug like this :
BEFORE :
this.getByteAt = function(iOffset) {
var block = getBlockAtOffset(iOffset);
if( typeof block.data == "string" ) {
AFTER :
this.getByteAt = function(iOffset) {
var block = getBlockAtOffset(iOffset);
if(typeof block === "undefined") return 0;
if( typeof block.data == "string" ) {
it's not perfect but it works. it don't give me an error fatal for my website.
i hope this can help you.
(sorry for my english, i'm french).