Traceback (innermost last):

    Module ZPublisher.Publish, line 126, in publish
    Module ZPublisher.mapply, line 77, in mapply
    Module Products.PDBDebugMode.runcall, line 70, in pdb_runcall
    Module ZPublisher.Publish, line 46, in call_object
    Module plone.app.portlets.browser.formhelper, line 125, in __call__
    Module zope.formlib.form, line 795, in __call__
    Module five.formlib.formbase, line 50, in update
    Module zope.formlib.form, line 758, in update
    Module zope.formlib.form, line 833, in setUpWidgets
    Module zope.formlib.form, line 412, in setUpEditWidgets
    Module zope.schema._bootstrapfields, line 186, in get

AttributeError: css_class