You asked for 1 a variable that doesnt exist. Backtrace:

#0  rsgGallery->get(id) called at [/home/.sites/114/site915/web/administrator/components/com_rsgallery2/includes/gallery.class.php:242]
#1  rsgGallery->rsgGallery() called at [/home/.sites/114/site915/web/administrator/components/com_rsgallery2/includes/gallery.class.php:140]
#2  rsgGalleryManager::_get(2) called at [/home/.sites/114/site915/web/administrator/components/com_rsgallery2/includes/gallery.class.php:29]
#3  rsgGalleryManager::get(2) called at [/home/.sites/114/site915/web/components/com_rsgallery2/rsgallery2.php:174]
#4  showImageInline() called at [/home/.sites/114/site915/web/components/com_rsgallery2/rsgallery2.php:67]
#5  require_once(/home/.sites/114/site915/web/components/com_rsgallery2/rsgallery2.php) called at [/home/.sites/114/site915/web/index.php:242]