should be testing for 'RenderGroup' in example

examples/main.cpp

@@ -128,7 +128,7 @@ loadSpaceShip(RenderState* rs)
 
 	// load model into gl
 	RenderGroup* rg = getFreeRenderGroup(rs);
-	assert(rs);
+	assert(rg);
 	initRenderGroup(rg, rs->rg_arena, shader_lit, 256, "ships");
 	Entity* e = getFreeEntity(rg);
 	assert(e);