Unable to add entity reference fields on Bookable calendar entities

Can confirm I get the same exact error. That is strange, checking around integer is a valid base field definition that is used in Drupal Core.

Here is an example from core core/lib/Drupal/Core/Entity/ContentEntityBase.php

$fields[$entity_type->getKey('id')] = BaseFieldDefinition::create('integer')
        ->setLabel(new TranslatableMarkup('ID'))
        ->setReadOnly(TRUE)
        ->setSetting('unsigned', TRUE);

Here is how this module does it.

$fields['slots'] = BaseFieldDefinition::create('integer')
      ->setLabel(t('Slots'))
      ->setDescription(t("The number of available slots for this instance. If empty (NB not zero), will use calendar's defaults."))
      ->setCardinality(1)
      ->setDisplayOptions('form', [
        'type' => 'integer',
        'weight' => 10,
      ])
      ->setSetting('min', 0)
      ->setDisplayConfigurable('form', TRUE)
      ->setDisplayConfigurable('view', TRUE);

I see other drupal core issues that address having the same issue not sure I see a solution yet though. I'll look and see if I can find anything.

Ok, now I see it. The problem is with this line of code:

      ->setDisplayOptions('form', [
        'type' => 'integer',
        'weight' => 10,
      ])

which should be:

      ->setDisplayOptions('form', [
        'widget_type' => 'integer',
        'weight' => 10,
      ])

This code change solves the problem in my case.

Good find, got that fixed and pushed to new version 2.2.9.

Automatically closed - issue fixed for 2 weeks with no activity.