Creating Media Type gives this Error: Call to a member function getName()

I had File Types, before starting to use 8.5.1 Media module.

I was using these contrib mod, then wanted to start using Media module in core. I updated db before enabling media module.

• "drupal/file_browser": "dev-1.x",
• "drupal/entity_embed": "dev-1.x",
• "drupal/entity_browser": "dev-1.x",
• "drupal/file_entity": "^2.0@beta",

When I go to /admin/structure/media/add to add a new image type (there are none currently), on submit I get this error.

The website encountered an unexpected error. Please try again later.

Error: Call to a member function getName() on null in Drupal\media\MediaSourceBase->prepareFormDisplay() (line 350 of core/modules/media/src/MediaSourceBase.php).
Drupal\media\MediaSourceBase->prepareFormDisplay(Object, Object) (Line: 362)
Drupal\media\MediaTypeForm->save(Array, Object)
call_user_func_array(Array, Array) (Line: 111)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers(Array, Object) (Line: 51)
Drupal\Core\Form\FormSubmitter->doSubmitForm(Array, Object) (Line: 585)
Drupal\Core\Form\FormBuilder->processForm('media_type_add_form', Array, Object) (Line: 314)
Drupal\Core\Form\FormBuilder->buildForm('media_type_add_form', Object) (Line: 74)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 582)
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: 99)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 50)
Drupal\ban\BanMiddleware->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 50)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 664)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

Then, when I go to the media type page, I can see my new type. If I click edit I get:

The website encountered an unexpected error. Please try again later.
Error: Call to a member function getLabel() on null in Drupal\media\MediaSourceBase->buildConfigurationForm() (line 199 of core/modules/media/src/MediaSourceBase.php).
Drupal\media\MediaSourceBase->buildConfigurationForm(Array, Object) (Line: 159)
Drupal\media\MediaTypeForm->form(Array, Object) (Line: 117)
Drupal\Core\Entity\EntityForm->buildForm(Array, Object)
call_user_func_array(Array, Array) (Line: 514)
Drupal\Core\Form\FormBuilder->retrieveForm('media_type_edit_form', Object) (Line: 271)
Drupal\Core\Form\FormBuilder->buildForm('media_type_edit_form', Object) (Line: 74)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 582)
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: 99)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 50)
Drupal\ban\BanMiddleware->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 50)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 664)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

Then, If I rather click Manage Fields, I am able see the field Image (field_media_image) and can edit this.

Not sure what to do about these errors?