Importing html image with no source and then exporting it to pdf causes an exception, instead of omitting the faulty image.

Such images can be stripped using the following workaround:

List<ImageInline> images = this.document.EnumerateChildrenOfType<ImageInline>().ToList();

foreach (var image in images)
{
      if (image.Image.ImageSource == null)
      {
               image.Paragraph.Inlines.Remove(image);
      }
}