Calling mWindow->update() before terrain loaded crashes

I just switched my project from TSM to PLSM; I currently have a loading screen which I switch to during map loading which calls mWindow->update() .
Now that I switched to PLSM, my application crashes if i try to call mWindow->update() before PLSM has loaded the terrain. Anyone have any ideas as to a workaround/fix for this?

In fact, plsm crash if you call the update method before the setWorldGeometry (or something like that) one.
Once you've done that, plsm start to load your terrain data, but you can already render frames at this point (loading bar, for example).
If you want to render something before, you got to create another SceneManager.