TypeError thrown

Argument 1 passed to lsolesen\pel\PelJpeg::setExif() must be an instance of lsolesen\pel\PelExif, null given, called in /web/htdocs/www.ashanet.it/home/home/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/nextgen_data/pel-0.9.6/class.exif_writer.php on line 121