Example trace:
[30-Sep-2020 14:36:01 UTC] PHP Warning: Invalid argument supplied for foreach() in /srv/mediawiki/tags/2020-09-25_13:55:54/includes/parser/ParserOptions.php on line 1411 [2020-09-30 14:36:01] error.ERROR: [6380379351ad2a807748480b] /wiki/Support ErrorException from line 1397 of /srv/mediawiki/tags/2020-09-25_13:55:54/includes/parser/ParserOptions.php: PHP Warning: array_intersec t(): Expected parameter 1 to be an array, null given {"exception":"[object] (ErrorException(code: 0): PHP Warning: array_intersect(): Expected parameter 1 to be an array, null given at /srv/mediawiki/tags/2020-09- 25_13:55:54/includes/parser/ParserOptions.php:1397) [stacktrace] #0 [internal function]: MWExceptionHandler::handleError(2, 'array_intersect...', '/srv/mediawiki/...', 1397, Array) #1 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/parser/ParserOptions.php(1397): array_intersect(NULL, Array, Array) #2 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/parser/ParserCache.php(251): ParserOptions->optionsHash(NULL, Object(Title)) #3 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/parser/ParserCache.php(283): ParserCache->getKey(Object(WikiPage), Object(ParserOptions), 0) #4 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/page/WikiPage.php(1208): ParserCache->get(Object(WikiPage), Object(ParserOptions)) #5 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/page/Article.php(2307): WikiPage->getParserOutput(Object(ParserOptions), NULL) #6 /srv/mediawiki/tags/2020-09-25_13:55:54/extensions/LiquidThreads/classes/View.php(1413): Article->getParserOutput(NULL) #7 /srv/mediawiki/tags/2020-09-25_13:55:54/extensions/LiquidThreads/classes/View.php(1570): LqtView->showPostBody(Object(Article), NULL) #8 /srv/mediawiki/tags/2020-09-25_13:55:54/extensions/LiquidThreads/classes/View.php(1826): LqtView->showThreadBody(Object(Thread)) #9 /srv/mediawiki/tags/2020-09-25_13:55:54/extensions/LiquidThreads/classes/View.php(2169): LqtView->showSingleThread(Object(Thread)) #10 /srv/mediawiki/tags/2020-09-25_13:55:54/extensions/LiquidThreads/pages/TalkpageView.php(362): LqtView->showThread(Object(Thread)) #11 /srv/mediawiki/tags/2020-09-25_13:55:54/extensions/LiquidThreads/classes/Dispatch.php(66): TalkpageView->show() #12 /srv/mediawiki/tags/2020-09-25_13:55:54/extensions/LiquidThreads/classes/Dispatch.php(222): LqtDispatch::talkpageMain(Object(OutputPage), Object(Article), Object(Title), Object(User), Object(WebRequest)) #13 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/HookContainer/HookContainer.php(331): LqtDispatch::tryPage(Object(OutputPage), Object(Article), Object(Title), Object(User), Object(WebRequest), Object(MediaWik i)) #14 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/HookContainer/HookContainer.php(138): MediaWiki\\HookContainer\\HookContainer->callLegacyHook('MediaWikiPerfor...', Array, Array, Array) #15 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/HookContainer/HookRunner.php(2543): MediaWiki\\HookContainer\\HookContainer->run('MediaWikiPerfor...', Array) #16 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/MediaWiki.php(499): MediaWiki\\HookContainer\\HookRunner->onMediaWikiPerformAction(Object(OutputPage), Object(Article), Object(Title), Object(User), Object(WebR equest), Object(MediaWiki)) #17 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/MediaWiki.php(313): MediaWiki->performAction(Object(Article), Object(Title)) #18 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/MediaWiki.php(940): MediaWiki->performRequest() #19 /srv/mediawiki/tags/2020-09-25_13:55:54/includes/MediaWiki.php(543): MediaWiki->main() #20 /srv/mediawiki/tags/2020-09-25_13:55:54/index.php(53): MediaWiki->run() #21 /srv/mediawiki/tags/2020-09-25_13:55:54/index.php(46): wfIndexMain() #22 {main} ","exception_id":"6380379351ad2a807748480b","exception_url":"/wiki/Support","caught_by":"mwe_handler"} []
Must have been introduced in last 7 days.