SearchApiSolrHighlightedFormatterSettingsTrait Warning: foreach() argument must be of type array|object, string given ... line 109

Warning: foreach() argument must be of type array|object, string given in Drupal\search_api_solr\Plugin\Field\FieldFormatter\SearchApiSolrHighlightedTextDefaultFormatter->getHighlightedValue() (line 109 of modules/contrib/search_api_solr/src/Plugin/Field/FieldFormatter/SearchApiSolrHighlightedFormatterSettingsTrait.php).

When looking at the query_keys call right before the getKeys() method can return array|string|null. So in the case of a string we get this error.