The Capo
godless Heathen
You could try replacing all of those with NONE to see if it fixes the assertion error, but do some thorough testing to make sure that works. Or you could just remove that resource that you aren't using.
I'll try both options there, the only thing that is concerning me about this though is that I didn't write this code. It is straight from Cultural Citystyles, which I know a lot of mods use. And I'm sure a lot of those mods don't use Tobacco so I guess I'm wondering why, if that is what is causing this, has nobody complained about it before? And also, I've had CC in my mod since I started working on it (basically) and didn't get this problem until I added Machu Picchu.
I'm not sure if you know this or not, but Machu Picchu does add a new improvement to the game (i.e. the "Machu Picchu improvement" that shows up on one of the peaks), GIR didn't have any CIV4PlotLSystem.xml file in his mod, so I assume it isn't necessary to edit that, but perhaps that could be the cause. I'll let you know what happens...
EDIT: Actually wait, since I get four or five (I think it is five) of those pop-ups, should I see if there are five resources I am not using?
EDIT 2: I just quickly looked and I see Olives, Tobacco, and Cotton, which I know are not standard civ resources. I'l look some more, you think maybe it is because of these extra resources? I'm thinking people probably didn't mention it because they probably didn't check it out, nor did the creator, and I may have started getting this assert after I enabled the debugging, so that could be what's going on here.