public function maybeEmptyNumericConfigArrays(array $base, array $merge): array
    {
        if (!$merge) { // Save time. Merge is empty?
            return $base; // Nothing to do here.
        }
        foreach ($base as $_key => &$_value) {
            if (is_array($_value) && array_key_exists($_key, $merge)) {
                if (!$_value || $_value === array_values($_value)) {
                    $_value = []; // Empty numeric arrays.
                } elseif ($merge[$_key] && is_array($merge[$_key])) {
                    $_value = $this->maybeEmptyNumericConfigArrays($_value, $merge[$_key]);
                }
            }
        } // unset($_key, $_value); // Housekeeping.
        return $base; // Return possibly-modified base.
    }