This should be fixed in the next release and on your server now. The code that is complaining here was written expecting that full page records would always be passed to it in order to extract types. However, via the process of trying to "find" URLs for BB-Code links, full page records are not available when the URL generator tries the content-type as a path determinate.
I am not yet sure if this happens everywhere a wiki link is used or only with certain usages. I would expect if it happened in all cases, there would be more reports, or the importer would fail for people on pages containing links.
Anyway, due to another bug which may have given a database error when you renamed the area, the area's name would be changed in the Area Manager, but not when viewing the page of the area (if you can even access it - the URL might be wrong). I have fixed the cause of this for the next release and on your server as well. I would recommend saving that area again if you notice the new title hasn't quite stuck.