I want to add some custom field. But I still got error even with the minimum amount of change

This is my attempt

        <!-- Question widgets -->
        <template id="survey.question_container_inherit" name="Survey: question container inherit prestaterre" inherit_id="survey.question_container" >
            <xpath expr="//t[@t-set='display_question']" position="after">
                <t t-set="hidden" t-value="any(item in hidden_protocol.get(question.mention_id.id, []) for item in selected_answers_requirement)"/>
            </xpath>
        </template>

And I got this error

Actually my code is much longer than this. And if the code above is working, it will not change anything in the view

but if this small change get error, the longer one won't run either