ClassViewSet retorna todos os resultados se usuário não tiver nenhum role configurado

[laurybueno]

Problema aparece no get_queryset da classe

timtec/core/views.py

    def get_queryset(self):
        queryset = super(ClassViewSet, self).get_queryset()
        if self.request.user.is_staff or self.request.user.is_superuser:
            return queryset

        course_id = self.request.query_params.get('course')
        if course_id:
            try:
                role = self.request.user.teaching_courses.get(course__id=course_id).role
            except ObjectDoesNotExist:
                role = ''
            # if user is not coordinator or admin, only show his classes
            if not role or role == 'assistant':
                queryset = queryset.filter(assistant=self.request.user)

        return queryset