Удалось поймать ошибку
function downloadImage(url, callback){
console.log("downloading image: "+ url);
var image = new Image();
image.crossOrigin = "Anonymous";
image.onload = function() {
var canvas = document.createElement('canvas');
var ctx = canvas.getContext('2d');
canvas.width = image.naturalWidth;
canvas.height = image.naturalHeight;
ctx.drawImage(image, 0, 0);
try{
var pngBlob = canvas.toDataURL();
} catch(e){
callback("");
}
callback(pngBlob);
};
if(image.addEventListener) {
image.addEventListener('error', function (e) {
e.preventDefault(); // Prevent error from getting thrown
callback("");
});
} else {
// Old IE uses .attachEvent instead
image.attachEvent('onerror', function (e) {
callback("");
return false; // Prevent propagation
});
}
image.src = url;
}