I'm seeing this error on an existing talk page on a local wiki. Am running master MW and Flow, and have run maintenance/update.php. Other Flow pages on the wiki work fine.
[c392700c32f34f370999b617] Talk:Main_Page Error from line 136 of extensions/Flow/includes/Formatter/TopicListQuery.php: Cannot unpack array with string keys Backtrace: #0 extensions/Flow/includes/Formatter/TopicListQuery.php(40): Flow\Formatter\TopicListQuery->collectPostIds(array) #1 extensions/Flow/includes/Block/TopicListBlock.php(293): Flow\Formatter\TopicListQuery->getResults(array) #2 extensions/Flow/includes/View.php(225): Flow\Block\TopicListBlock->renderApi(array) #3 extensions/Flow/includes/View.php(70): Flow\View->buildApiResponse(Flow\WorkflowLoader, array, string, array) #4 extensions/Flow/includes/Actions/Action.php(112): Flow\View->show(Flow\WorkflowLoader, string) #5 extensions/Flow/includes/Actions/ViewAction.php(20): Flow\Actions\FlowAction->showForAction(string, OutputPage) #6 extensions/Flow/includes/Actions/Action.php(50): Flow\Actions\ViewAction->showForAction(string) #7 core/includes/MediaWiki.php(500): Flow\Actions\FlowAction->show() #8 core/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title) #9 core/includes/MediaWiki.php(867): MediaWiki->performRequest() #10 core/includes/MediaWiki.php(524): MediaWiki->main() #11 core/index.php(42): MediaWiki->run() #12 {main}