[{reqId}] {exception_url}   Error: Call to a member function getContent() on null

from /srv/mediawiki/php-1.37.0-wmf.23/extensions/Flow/includes/Import/OptInController.php(506)
#0 /srv/mediawiki/php-1.37.0-wmf.23/extensions/Flow/includes/Import/OptInController.php(689): Flow\Import\OptInController->editBoardDescription(Title, Closure, string)
#1 /srv/mediawiki/php-1.37.0-wmf.23/extensions/Flow/includes/Import/OptInController.php(183): Flow\Import\OptInController->archiveFlowBoard(Title)
#2 /srv/mediawiki/php-1.37.0-wmf.23/extensions/Flow/includes/Import/OptInController.php(120): Flow\Import\OptInController->disable(Title)
#3 /srv/mediawiki/php-1.37.0-wmf.23/includes/deferred/MWCallableUpdate.php(38): Flow\Import\OptInController->Flow\Import\{closure}()
#4 /srv/mediawiki/php-1.37.0-wmf.23/includes/deferred/DeferredUpdates.php(515): MWCallableUpdate->doUpdate()
#5 /srv/mediawiki/php-1.37.0-wmf.23/includes/deferred/DeferredUpdates.php(391): DeferredUpdates::attemptUpdate(MWCallableUpdate, Wikimedia\Rdbms\LBFactoryMulti)
#6 /srv/mediawiki/php-1.37.0-wmf.23/includes/deferred/DeferredUpdates.php(221): DeferredUpdates::run(MWCallableUpdate, Wikimedia\Rdbms\LBFactoryMulti, Monolog\Logger, BufferingStatsdDataFactory, string)
#7 /srv/mediawiki/php-1.37.0-wmf.23/includes/deferred/DeferredUpdatesScope.php(267): DeferredUpdates::{closure}(MWCallableUpdate, integer)
#8 /srv/mediawiki/php-1.37.0-wmf.23/includes/deferred/DeferredUpdatesScope.php(196): DeferredUpdatesScope->processStageQueue(integer, integer, Closure)
#9 /srv/mediawiki/php-1.37.0-wmf.23/includes/deferred/DeferredUpdates.php(242): DeferredUpdatesScope->processUpdates(integer, Closure)
#10 /srv/mediawiki/php-1.37.0-wmf.23/includes/MediaWiki.php(1136): DeferredUpdates::doUpdates(string)
#11 /srv/mediawiki/php-1.37.0-wmf.23/includes/MediaWiki.php(846): MediaWiki->restInPeace()
#12 /srv/mediawiki/php-1.37.0-wmf.23/includes/MediaWiki.php(584): MediaWiki->doPostOutputShutdown()
#13 /srv/mediawiki/php-1.37.0-wmf.23/index.php(53): MediaWiki->run()
#14 /srv/mediawiki/php-1.37.0-wmf.23/index.php(46): wfIndexMain()
#15 /srv/mediawiki/w/index.php(3): require(string)
#16 {main}