https://en.wikipedia.beta.wmflabs.org/wiki/Special:RecentChanges shows
[WNP6lQpEE4AAAGFTkFAAAAAK] /wiki/Special:RecentChanges MWException from line 257 of /srv/mediawiki/php-master/includes/changes/ChangesListFilter.php: You can only pass in a ChangesListFilterGroup or a ChangesListFilter Backtrace: #0 /srv/mediawiki/php-master/includes/changes/ChangesListFilter.php(219): ChangesListFilter->setUnidirectionalConflict(NULL, string, string) #1 /srv/mediawiki/php-master/extensions/Wikidata/extensions/Wikibase/client/includes/Hooks/ChangesListSpecialPageHookHandlers.php(241): ChangesListFilter->conflictsWith(NULL, string, string, string) #2 /srv/mediawiki/php-master/extensions/Wikidata/extensions/Wikibase/client/includes/Hooks/ChangesListSpecialPageHookHandlers.php(200): Wikibase\Client\Hooks\ChangesListSpecialPageHookHandlers->addFilter(SpecialRecentChanges) #3 /srv/mediawiki/php-master/extensions/Wikidata/extensions/Wikibase/client/includes/Hooks/ChangesListSpecialPageHookHandlers.php(133): Wikibase\Client\Hooks\ChangesListSpecialPageHookHandlers->addFilterIfEnabled(SpecialRecentChanges) #4 /srv/mediawiki/php-master/includes/Hooks.php(186): Wikibase\Client\Hooks\ChangesListSpecialPageHookHandlers::onChangesListSpecialPageStructuredFilters(SpecialRecentChanges) #5 /srv/mediawiki/php-master/includes/specialpage/ChangesListSpecialPage.php(512): Hooks::run(string, array) #6 /srv/mediawiki/php-master/includes/specials/SpecialRecentchanges.php(110): ChangesListSpecialPage->registerFilters() [...]
It looks like the NULL being passed into conflictsWith() comes from $damagingGroup = $specialPage->getFilterGroup( 'damaging' );. So our hack for making sure the Wikidata hook runs after the ORES hook doesn't seem to work on beta. (It did work for me locally.)