Custom rule does not work if the field value is null and can be nullable

[Cepairda]

Package

Panel builder

Package Version

3.3.0

How can we help you?

Hello everyone. I made a custom rule. If the driver has an active shift, then you can't change the driver in select. Everything works fine, if I change to another driver, then I get an error.
But if I delete the driver through the standard delete icon, then there is no error.
The rule does not work. Thanks for your help

public static function form(Form $form): Form
    {
        return $form
            ->schema([
                Forms\Components\Select::make('driver_id')
                    ->label('Водитель')
                    ->relationship(
                        'driver',
                        'first_name',
                        modifyQueryUsing: function (Builder $query, ?Car $record) {
                            $query
                                ->when($record, fn (Builder $query) => $query->whereId($record->driver_id))
                                ->orWhere(fn (Builder $query) => $query->whereDoesntHave('car'));
                        }
                    )
                    ->searchable()
                    ->preload()
                    ->reactive()
                    ->live()
                    ->afterStateUpdated(function (
                        $state,
                        $record,
                        callable $set,
                        Forms\Contracts\HasForms $livewire,
                        Forms\Components\Select $component
                    ) {
                        $livewire->validateOnly($component->getStatePath());
                        $set('is_available', !$state);

                        if ($record) {
                            if ($state) {
                                $record->assignDriver($state);
                            } else {
                                $record->removeDriver();
                            }
                        }
                    })
                    ->rules([
                        function ($get, $set, $record) {
                            return function (string $attribute, $value, Closure $fail) use ($record) {
                                if (!$record) {
                                    return;
                                }

                                if ($record->driver_id == $value) {
                                    return;
                                }

                                $oldDriver = $record->driver;

                                if ($oldDriver && $oldDriver->is_shift) {
                                    $fail('You cannot change a driver while the current driver has an active shift.');
                                }
                            };
                        }
                    ]),
                Forms\Components\Toggle::make('is_available')
                    ->required()
                    ->default(true)
                    ->disabled(),
            ]);
    }

`