[kh99]

Oh, yeah, that script is not meant to be visited directly. It's only meant to be included by other scripts, which would have the database object created already. But to be honest I don't really understand the reasoning behind doing that check since the only thing in the file is a class definition.

ETA: I notice that it's at the top of many files, so I guess it's a standard thing that they decided to put at the top of each file that's meant to only be included, to head off any unforseen issues if someone accesses it directly.