add FIXME in loadScene about reusing attrib_mappings

src/main.cpp

@@ -297,6 +297,8 @@ loadScene(RenderState* rs)
 			"orange_cubes");
 	Entity* e = getFreeEntity(debug_cube_group);
 	assert(e != nullptr);
+	// FIXME: this a bug, we're reusing the attrib_mappings from the debug
+	// 	shader for the default shader, which could have different attributes
 	initEntity(e, rs->rg_arena, tex_cube, 2, attrib_mappings, "orange_box");
 
 	return true;