AggregateModel with referenced field in expression throwing error about data HOT 2 CLOSED

class Account extends Model
{
    public $table = 'account';

    protected function init(): void
    {
        parent::init();
        $this->addFields(['name', 'fx_rate' => ['type' => 'float']]);
    }
}

class Booking extends Model
{
    public $table = 'booking';

    protected function init(): void
    {
        parent::init();
        $this->addFields(['booking_group', 'value' => ['type' => 'float']]);
        $this->hasOne('account_id', ['model' => [Account::class]])->addField('fx_rate');
    }
}

    public function testAggregate1078(): void
    {
        $m = new Model($this->db, ['table' => 'account']);
        $m->addField('name');
        $m->addField('fx_rate', ['type' => 'float']);
        $this->createMigrator($m)->create();

        $m->import([
            ['name' => 'Test Account', 'fx_rate' => 1.2],
        ]);

        $m = new Model($this->db, ['table' => 'booking']);
        $m->addField('account_id', ['type' => 'integer']);
        $m->addField('booking_group');
        $m->addField('value', ['type' => 'float']);
        $this->createMigrator($m)->create();

        $m->import([
            ['account_id' => 1, 'booking_group' => 'Group1', 'value' => 123],
            ['account_id' => 1, 'booking_group' => 'Group1', 'value' => 456],
            ['account_id' => 1, 'booking_group' => 'Group2', 'value' => 789],
        ]);

        $accountModel = new Account($this->db);
        $bookingModel = new Booking($this->db);

        $bookingAggregate = new AggregateModel($bookingModel);
        $bookingAggregate->setGroupBy(['booking_group'], [
            'total' => ['expr' => 'sum([value])'], ]);

        foreach ($bookingAggregate as $booking) {
            echo 'Result: ' . $booking->get('booking_group') . ' | ' . $booking->get('total');
        }

        echo 'That worked..';

        $bookingAggregate = new AggregateModel($bookingModel);
        $bookingAggregate->setGroupBy(['booking_group'], [
            'total' => ['expr' => 'sum([fx_rate] * [value])'], ]);

        foreach ($bookingAggregate as $booking) {
            echo 'Result: ' . $booking->get('total');
        }
        echo 'That did not work..';
    }