Added sanity checks to 'Igor.delete' method.
Added sanity checks to 'Igor.delete' method.

daviddeng/azrael,olitheolix/azrael,daviddeng/azrael,olitheolix/azrael,olitheolix/azrael,daviddeng/azrael,olitheolix/azrael,daviddeng/azrael,daviddeng/azrael,olitheolix/azrael