When loading the Wikisource extension without ProofreadPage, the following error is shown:
Original exception: [d5d6f99416d69000a91e7f03] /Index:Test_doc.pdf Error: Class "ProofreadPage\ProofreadPageInit" not found
Backtrace:
from /mediawiki/extensions/Wikisource/includes/HookHandler/BeforePageDisplayHandler.php(49)
#0 /mediawiki/includes/HookContainer/HookContainer.php(155): MediaWiki\Extension\Wikisource\HookHandler\BeforePageDisplayHandler->onBeforePageDisplay()
#1 /mediawiki/includes/HookContainer/HookRunner.php(995): MediaWiki\HookContainer\HookContainer->run()
#2 /mediawiki/includes/Output/OutputPage.php(3284): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay()
#3 /mediawiki/includes/actions/ActionEntryPoint.php(160): MediaWiki\Output\OutputPage->output()
#4 /mediawiki/includes/MediaWikiEntryPoint.php(198): MediaWiki\Actions\ActionEntryPoint->execute()
#5 /mediawiki/index.php(58): MediaWiki\MediaWikiEntryPoint->run()
#6 {main}