Update app.py

app.py

@@ -299,7 +299,11 @@ stop_button = st.button("Stop Simulation", on_click=stop_simulation)
 while True:
     try:
         fig = q.get(timeout=0.1)
-        chart_placeholder.plotly_chart(fig, use_container_width=True)
+        if fig is not None:
+            chart_placeholder.plotly_chart(fig, use_container_width=True)
+        else:
+            print("Received None figure from queue. Stopping simulation.")
+            break
     except queue.Empty:
         time.sleep(0.1)
         continue