Libraries referencing models?

I have been perusing the source code for instiki (http://
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classes, there are references to model classes. And of course model
classes refer to library classes.

When deployed in production mode, everything works, but if you deploy
instiki in development mode, a superclass mismatch error occurs.

It strikes me that this tight coupling is a bad design: models should
refer to libraries, but not vice versa. Otherwise, there is no
separation of concern.