[BUG] Exception in SOLR_RELATION if relation is not translated

[dkd-friedrich]

Describe the bug

Indexing of a translated record with relation to a non-translated record causes an exception

ApacheSolrForTypo3\Solr\ContentObject\Relation::getRelatedItemsFromForeignTable(): Argument #2 ($localRecordUid) must be of type int, null given, called in vendor/apache-solr-for-typo3/solr/Classes/ContentObject/Relation.php on line 347

Expected behavior

No exception should occur and just no relation should be indexed.

Used versions (please complete the following information):

• TYPO3 Version: 12
• Used EXT:solr Version: 12.0.3