InvalidQueryException when dealing with user entities

Problem/Motivation

If you install group and entitygroupfield, and configure the account form display to use a group widget before you create any group types and configure any group content plugins, you get an InvalidQueryException:

Drupal\Core\Database\InvalidQueryException: Query condition 'groups_field_data.type IN ()' cannot be empty. in Drupal\Core\Database\Query\Condition->condition() (line 105 of core/lib/Drupal/Core/Database/Query/Condition.php).
Drupal\Core\Database\Query\Select->condition('groups_field_data.type', Array, 'IN') (Line: 61)
Drupal\Core\Entity\Query\Sql\Condition->compile(Object) (Line: 172)
Drupal\Core\Entity\Query\Sql\Query->compile() (Line: 80)
Drupal\Core\Entity\Query\Sql\Query->execute() (Line: 577)
Drupal\Core\Entity\EntityStorageBase->loadByProperties(Array) (Line: 49)
Drupal\entitygroupfield\Plugin\Field\FieldWidget\EntityGroupFieldSelectWidget->getPluginGroups() (Line: 64)
Drupal\entitygroupfield\Plugin\Field\FieldWidget\EntityGroupFieldSelectWidget->getAllowedGroups(, Array) (Line: 23)
Drupal\entitygroupfield\Plugin\Field\FieldWidget\EntityGroupFieldSelectWidget->buildAddElement(, Array) (Line: 753)
Drupal\entitygroupfield\Plugin\Field\FieldWidget\EntityGroupFieldWidgetBase->buildAddActions(, Array) (Line: 686)
Drupal\entitygroupfield\Plugin\Field\FieldWidget\EntityGroupFieldWidgetBase->formMultipleElements(Object, Array, Object) (Line: 113)
Drupal\Core\Field\WidgetBase->form(Object, Array, Object) (Line: 178)
Drupal\Core\Entity\Entity\EntityFormDisplay->buildForm(Object, Array, Object) (Line: 125)
Drupal\Core\Entity\ContentEntityForm->form(Array, Object, Object) (Line: 304)
Drupal\user\AccountForm->form(Array, Object, Object) (Line: 54)
Drupal\user\RegisterForm->form(Array, Object) (Line: 149)
Drupal\Core\Entity\EntityForm->buildForm(Array, Object)
call_user_func_array(Array, Array) (Line: 532)
Drupal\Core\Form\FormBuilder->retrieveForm('user_register_form', Object) (Line: 278)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 91)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 573)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 151)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 708)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

It should work for group_membership + user, but it doesn't.

Proposed resolution

Find and fix bug.

Remaining tasks

1. Figure out what's going wrong.
2. Fix it.
3. Expand test coverage to try with users, too.
4. Reviews/refinements.
5. RTBC.
6. Commit.

User interface changes

API changes

Data model changes

Release notes snippet