This is an error with the model based renderer and, if I am not mistaken, most likely indicates your graphics hardware does not support the features required to run it.
Note that this renderer has been available to Ren'Py based visual novels since January, however as of the last update to the engine is now the default. You will likely start seeing this in other Ren'Py based visual novels in the near future. At some point, the other renderers will be removed as well, so developers are being encouraged to make the transition.
The first thing I'd suggest is make sure your graphics drivers are up to date. In our internal testing we found that systems from roughly 2013 and newer had the necessary features to run this new renderer. Older systems generally did not, however some occasionally received support via a driver update.