img without src attribute set fails to load print preview

When trying to load the print preview page for an 'html' print nothing happens when i have an image element that has no src attribute value.
The 'loadIframeImage' pollImage function loops forever trying to load it, and so the preview never shows.
I got it working by checking if image.src is not empty here:

`function loadIframeImages(images) {` ....

if (image.src !== '') {
promises.push(loadIframeImage(image));
}
....

it's a hack for now, not sure if this is a permanent fix. had me scratching my head for a while as there were no console errors thrown for this.
Anyway; just logging in case it's something that can be fixed in the next version, or at least for anyone searching for a similar reason to their dilemma like i was.