PHP 8.5: Using null as an array offset is deprecated in QueryBuilder.php #631

// Before
$dictionary[null] = reset($dictionary);

// After
$dictionary[''] = reset($dictionary);

Method reorderNodes() (lines 943-966):
protected static function reorderNodes(
    array &$dictionary, array &$updated, $parentId = null, $cut = 1
) {
    $key = $parentId ?? '';

    if (! isset($dictionary[$key])) {
        return $cut;
    }

    foreach ($dictionary[$key] as $model) {
        $lft = $cut;

        $cut = self::reorderNodes($dictionary, $updated, $model->getKey(), $cut + 1);

        if ($model->rawNode($lft, $cut, $parentId)->isDirty()) {
            $updated[] = $model;
        }

        ++$cut;
    }

    unset($dictionary[$key]);

    return $cut;
}

Line 1007:
// Before
$dictionary[$model->getParentId()][] = $model;

// After
$dictionary[$model->getParentId() ?? ''][] = $model;

Line 1071:
// Before
$dictionary[$parentId][] = $model;

// After
$dictionary[$parentId ?? ''][] = $model;

Environment

- PHP 8.5
- Laravel 12
- kalnoy/nestedset v6.0.6