As of now, my devwiki shows this when visiting any page:
Original exception: [3753ffd4176511f43bc39d2a] /mw/ Error: Interface 'MediaWiki\Extension\VisualEditor\VisualEditorApiVisualEditorEditPostSaveHook' not found
Backtrace:
from /home/urbanecm/unsynced/gerrit/mediawiki/extensions/GrowthExperiments/includes/HomepageHooks.php(69)
#0 /home/urbanecm/unsynced/gerrit/mediawiki/core/includes/AutoLoader.php(126): require()
#1 [internal function]: AutoLoader::autoload()
#2 /home/urbanecm/unsynced/gerrit/mediawiki/core/includes/HookContainer/HookContainer.php(330): spl_autoload_call()
#3 /home/urbanecm/unsynced/gerrit/mediawiki/core/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#4 /home/urbanecm/unsynced/gerrit/mediawiki/core/includes/Hooks.php(137): MediaWiki\HookContainer\HookContainer->run()
#5 /home/urbanecm/unsynced/gerrit/mediawiki/extensions/Echo/includes/EchoHooks.php(92): Hooks::run()
#6 /home/urbanecm/unsynced/gerrit/mediawiki/core/includes/Setup.php(821): EchoHooks::initEchoExtension()
#7 /home/urbanecm/unsynced/gerrit/mediawiki/core/includes/WebStart.php(87): require_once(string)
#8 /home/urbanecm/unsynced/gerrit/mediawiki/core/index.php(44): require(string)
#9 {main}The issue seems to be that HomepageHooks uses MediaWiki\Extension\VisualEditor\VisualEditorApiVisualEditorEditPostSaveHook, which isn't guaranteed to exist – GrowthExperiments doesn't depend on anything but MediaWiki.