I've restored some sitelinks on https://www.wikidata.org/wiki/Q670593 after a editor wrongly switched them. After that, https://en.wikipedia.org/wiki/Wolfsberg,_Thuringia began to show the following error (leaving the rest of the page empty):
Exception encountered, of type "BadMethodCallException"
The full trace (thanks to @Legoktm):
2016-02-28 22:27:33 mw1217 enwiki 1.27.0-wmf.14 exception ERROR: [b158dc6e] /wiki/Wolfsberg,_Thuringia BadMethodCallException from line 300 of /srv/mediawiki/php-1.27.0-wmf.14/extensions/WikidataPageBanner/includes/WikidataPageBanner.functions.php: Call to a member function getStatements() on a non-object (NULL) {"exception_id":"b158dc6e"}
[Exception BadMethodCallException] (/srv/mediawiki/php-1.27.0-wmf.14/extensions/WikidataPageBanner/includes/WikidataPageBanner.functions.php:300) Call to a member function getStatements() on a non-object (NULL)
#0 /srv/mediawiki/php-1.27.0-wmf.14/extensions/WikidataPageBanner/includes/WikidataPageBanner.functions.php(241): WikidataPageBannerFunctions::getWikidataBanner(Title)
#1 /srv/mediawiki/php-1.27.0-wmf.14/extensions/WikidataPageBanner/includes/WikidataPageBanner.hooks.php(125): WikidataPageBannerFunctions::getAutomaticBanner(Title)
#2 /srv/mediawiki/php-1.27.0-wmf.14/includes/Hooks.php(195): WikidataPageBanner::onBeforePageDisplay(OutputPage, SkinVector)
#3 /srv/mediawiki/php-1.27.0-wmf.14/includes/OutputPage.php(2354): Hooks::run(string, array)
#4 /srv/mediawiki/php-1.27.0-wmf.14/includes/MediaWiki.php(746): OutputPage->output()
#5 /srv/mediawiki/php-1.27.0-wmf.14/includes/MediaWiki.php(519): MediaWiki->main()
#6 /srv/mediawiki/php-1.27.0-wmf.14/index.php(43): MediaWiki->run()
#7 /srv/mediawiki/w/index.php(3): include(string)
#8 {main}