Add an error throw for popping empty stack

starfish.js

@@ -555,7 +555,10 @@ class Stack {
      * @returns {*}
      */
     Pop() {
-        return this.stack.pop();
+        const value = this.stack.pop();
+        if(value == undefined){ throw new Error(); }
+
+        return value;
     }
 
     /**