In versions before 6.x these errors intentionally didn't cause
the startup fail, but I think we can be more strict now.
{% macro local_data_addresses(pairs) -%}
{% for name, address in pairs.items() %}
-hints['{{ name }}'] = '{{ address }}'
+assert(hints.set('{{ name }} {{ address }}').result == true)
{% endfor %}
{%- endmacro %}
{% macro local_data_addresses_files(files) -%}
{% for file in files %}
-hints.add_hosts('{{ file }}')
+assert(hints.add_hosts('{{ file }}').result == true)
{% endfor %}
{%- endmacro %}