Add missing success check to ApiQueryMapData
Add missing success check to ApiQueryMapData

I found this error via logstash.wikimedia.org. The method
getParserOutput() can return false in case a page can't be
found or is restricted.

Change-Id: Ib6a568a81084ffbb7683f354c8b10b9f42f2d1e7

wikimedia/mediawiki-extensions-Kartographer,wikimedia/mediawiki-extensions-Kartographer,wikimedia/mediawiki-extensions-Kartographer