节点池代码优化

assets/script/mk/system/PoolSystem.ts

@@ -43,7 +43,7 @@ export default class PoolSystem {
         } else {
             let prefab = await mk.loader.load(url, cc.Prefab);
             node = cc.instantiate(prefab);
-            pool.put(node);
+            pool && pool.put(node);
         }
         return node;
     }
@@ -54,7 +54,8 @@ export default class PoolSystem {
      * @param node 
      */
     return(name, node: cc.Node) {
-        node.destroy();
+        // node.destroy();
+        node.removeFromParent();
         let pool = this.poolList[name];
         if (pool) {
             pool.put(node);