fix generate no recursive

Author: BruceZhang1993

index_generator/__main__.py

@@ -43,7 +43,7 @@ def app(args):
     if args.no_recursive:
         os.chdir(args.path)
         generate_once(args.theme, '.', os.listdir('.'), args.name, args.print, base=args.root, human=args.human,
-                      template=os.path.abspath(args.template))
+                      template=os.path.abspath(args.template) if args.template else '')
     else:
         generate_recursively(args.theme, args.path, args.name, args.print, args.depth, base=args.root, human=args.human,
                              template=os.path.abspath(args.template))