From dad82050f82706ab3773dbf528a904968d38d385 Mon Sep 17 00:00:00 2001
From: Adrian Orenstein <adrian.orenstein@gmail.com>
Date: Sun, 25 Aug 2024 20:49:27 -0600
Subject: [PATCH] if box contains nothing, do nothing

---
 minigrid/core/world_object.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/minigrid/core/world_object.py b/minigrid/core/world_object.py
index a1fe01911..6e97943b7 100644
--- a/minigrid/core/world_object.py
+++ b/minigrid/core/world_object.py
@@ -288,6 +288,10 @@ def render(self, img):
         fill_coords(img, point_in_rect(0.16, 0.84, 0.47, 0.53), c)
 
     def toggle(self, env, pos):
+        # if the box is empty, do nothing
+        if self.contains is None:
+            return False
+
         # Replace the box by its contents
         env.grid.set(pos[0], pos[1], self.contains)
         return True