Error message

• Notice: Undefined index: und in oyster_gallery_grid_alt() (line 313 of /home/menelaosp/public_html/sites/all/modules/oyster_gallery/inc/oyster_gallery_block.inc).
• Warning: Invalid argument supplied for foreach() in oyster_gallery_grid_alt() (line 313 of /home/menelaosp/public_html/sites/all/modules/oyster_gallery/inc/oyster_gallery_block.inc).