Error !

AttributeError: 'NoneType' object has no attribute 'render'

if not frontpage: frontpage = object.first('frontpage-6-6') %> ${ frontpage.render() }
templates/default/project, line 7:
${ frontpage.render() }
/venv/lib/python2.7/site-packages/mako/runtime.py, line 890:
callable_(context, *args, **kwargs)
/venv/lib/python2.7/site-packages/mako/runtime.py, line 864:
_exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
/venv/lib/python2.7/site-packages/mako/runtime.py, line 829:
**_kwargs_for_callable(callable_, data))
/venv/lib/python2.7/site-packages/mako/template.py, line 445:
return runtime._render(self, self.callable_, args, data)
/home/lime/docker-inst/Products/LimeTemplate/LimeTemplate.py, line 722:
html = mytemplate.render(object=object, site=site, request=self.REQUEST, extra=extra.get('kwargs', None), **extra)