Export of an index contains blank Module Dependency

Just ran into same problem

Had the same issue.
I had a computed (views) field in my index. I could fix that problem by removing that field from index

Thanks for reporting this problem!
However, as it doesn’t seem easily possible to reproduce this problem, I’d need help in investigating its root cause. The problem appears very likely somewhere in \Drupal\search_api\Entity\Index::getDependencyData(). Would you be able to step through that, or add debugging lines, to see when and from where the empty module dependency is added?

I've the same problem creating and index to index content from https://www.drupal.org/project/recurring_events → .

In the index configuration i check: Event Instance entity, Event series entity and Registrant.

I hope it helps you, this error is quite annoying.

I had ran into this when indexing a computed field with an unset provider, e.g.

$fields['computed_field'] = BaseFieldDefinition::create('string')
      ->setLabel(t('Example computed field'))
      ->setReadOnly(TRUE)
      ->setComputed(TRUE)
      ->setClass(ExampleComputedField::class)
      ->setDisplayConfigurable('form', FALSE)
      ->setDisplayConfigurable('view', TRUE)
      ->setProvider('example_computed_field'); // <---

I haven't stepped through the code but would make sense given the following in `\Drupal\search_api\Entity\Index::getDependencyData()`:

$type_dependencies[$type]['module'][] = $definition['provider'];

That line doesn’t really refer to a field definition, but to a data type. Still, easy to check whether this might be the cause – please test the attached patch and see if it resolves the issue for you.