change

source/scripts/engine.js

@@ -1505,6 +1505,10 @@ var gameobject = {
   stop() {},
 
   kill() {
+    if (this.body === -1) {
+      Log.warn(`Object is already dead!`);
+      return;
+    }
     Register.endofloop(() => {
       cmd(2, this.body);
       delete Game.objects[this.body];