Proper error handling

examples/simple.lua

@@ -3,6 +3,10 @@ config:set_background_color(Color(20, 20, 30))
 config:set_fps(60)
 config:set_num_layers(5)
 
+-- test(function(i)
+--     return i
+-- end)
+
 layer(0)
 draw(Rect(Point(100, 100), Size(200, 150), Color(255, 100, 100, 255)))
 layer(1)
@@ -23,7 +27,6 @@ animate(Animation(
 
 layer(2)
 
-
 animate(Animation(
     CircleOutline(
         Point(400.0, 300.0),