PHPUnit 10 marks empty data provider as invalid with the text "Empty data set provided by data provider" and count this as errors.
Some implementation of EntityHandlerTestCase seems to provide empty data provider or calling markTestSkipped
There was 3 PHPUnit error: 1) Wikibase\Lexeme\Tests\MediaWiki\Content\LexemeHandlerTest::testGetUndoContent The data provider specified for Wikibase\Lexeme\Tests\MediaWiki\Content\LexemeHandlerTest::testGetUndoContent is invalid provideGetUndoContent only works for entities that have labels field WikibaseLexeme\tests\phpunit\mediawiki\Content\LexemeHandlerTest.php:343 2) Wikibase\Search\Elastic\Tests\ItemHandlerTest::testSerialization The data provider specified for Wikibase\Search\Elastic\Tests\ItemHandlerTest::testSerialization is invalid Empty data set provided by data provider WikibaseCirrusSearch\tests\phpunit\ItemHandlerTest.php:189 3) Wikibase\Search\Elastic\Tests\PropertyHandlerTest::testSerialization The data provider specified for Wikibase\Search\Elastic\Tests\PropertyHandlerTest::testSerialization is invalid Empty data set provided by data provider WikibaseCirrusSearch\tests\phpunit\PropertyHandlerTest.php:189