Error !

TypeError: expected string or buffer

<%inherit file="site" /> <%def name="main_content()"> <% import json topitem = object while topitem.aq_parent.meta_type != 'LimeSite': topitem = topitem.aq_parent leftmenu = topitem.getMenuItems()
/usr/lib/python2.7/json/decoder.py, line 366:
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
/usr/lib/python2.7/json/__init__.py, line 338:
return _default_decoder.decode(s)
templates/trenett/project, line 6:
<%
templates/trenett/site, line 94:
${self.main_content()}
/srv/limenine_data/limecms/trefokus/trefokus01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/runtime.py, line 890:
callable_(context, *args, **kwargs)
/srv/limenine_data/limecms/trefokus/trefokus01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/runtime.py, line 864:
_exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
/srv/limenine_data/limecms/trefokus/trefokus01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/runtime.py, line 829:
**_kwargs_for_callable(callable_, data))
/srv/limenine_data/limecms/trefokus/trefokus01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/template.py, line 445:
return runtime._render(self, self.callable_, args, data)
/var/limecms/trefokus/trefokus01/trefokus-inst/Products/LimeTemplate/LimeTemplate.py, line 667:
html = mytemplate.render(object=object, site=site, extra=extra.get('kwargs', None), **extra)