Previously, it was not possible to distinguish between value `0` and not selected (`zero`).
{foreach from=$field->getNestedOptions() item=__fieldNestedOption}
<option
value="{$__fieldNestedOption[value]}"
- {if $field->getValue() == $__fieldNestedOption[value] && $__fieldNestedOption[isSelectable]} selected{/if}
+ {if $field->getValue() !== null && $field->getValue() == $__fieldNestedOption[value] && $__fieldNestedOption[isSelectable]} selected{/if}
{if $field->isImmutable() || !$__fieldNestedOption[isSelectable]} disabled{/if}
>{@' '|str_repeat:$__fieldNestedOption[depth] * 4}{@$__fieldNestedOption[label]}</option>
{/foreach}