ERROR: object of type 'NoneType' has no len()

Traceback (most recent call last):
  File "/var/www/desktop.in.ua/core/app.py", line 104, in run
    self.view()
  File "/var/www/desktop.in.ua/core/app.py", line 176, in view
    self.Registry.template_data))
  File "/var/www/desktop.in.ua/core/system.py", line 208, in render
    html = Data.encode(T.render(**data))
  File "/usr/lib/pymodules/python2.6/jinja2/environment.py", line 891, in render
    return self.environment.handle_exception(exc_info, True)
  File "/var/www/desktop.in.ua/sites/desktopinua/templates/product.html", line 1, in top-level template code
    {% extends "base.html" %}
  File "/var/www/desktop.in.ua/sites/desktopinua/templates/base.html", line 114, in top-level template code
    {% block main %}{% endblock %}
  File "/var/www/desktop.in.ua/sites/desktopinua/templates/product.html", line 135, in block "main"
    
{{ item.name|truncate(33) }}
  File "/usr/lib/pymodules/python2.6/jinja2/filters.py", line 374, in do_truncate
    if len(s) <= length:
TypeError: object of type 'NoneType' has no len()