src/Buttons/BetterButton_SaveAndNext.php
public function baseTransform()
    {
        parent::baseTransform();
        $disabled = (!$this->gridFieldRequest->getNextRecordID());

        return $this->setDisabled($disabled);
    }
public function baseTransform()
    {
        parent::baseTransform();
        $disabled = (!$this->gridFieldRequest->getNextRecordID());

        return $this->setDisabled($disabled);
    }
Disables the button if there is no next record
@return FormAction