@fixme this is probably *horribly wrong*

@fixme this is probably *horribly wrong*
LanguageConverter seems to want $wgParser's uniqPrefix, however
if this is called for a parser cache hit, the parser may not
have ever been initialized in the first place.

Not really sure what the heck is supposed to be going on here...
For now, returning an empty string '' without dying out, but
leaving a stub exception comment in for testing.