fix(wish-tree): 修复切换树后导航消失和树类型错误

- loadWishes使用safeInitRibbons/safeInitDanmaku，防止初始化出错导致页面崩溃
- getCurrentTree确保返回带type字段的有效树对象
- 添加错误处理，避免未定义错误

mini/pages/wish-tree/wish-tree.js

@@ -172,8 +172,8 @@ Page({
       
       if (res.code === 0) {
         this.setData({ wishes: res.data.list || [] });
-        this.initRibbons();
-        this.initDanmaku();
+        this.safeInitRibbons();
+        this.safeInitDanmaku();
       }
     } catch (err) {
       console.error('加载许愿失败:', err);
@@ -181,8 +181,28 @@ Page({
       this.setData({
         wishes: this.getMockWishes(),
       });
+      this.safeInitRibbons();
+      this.safeInitDanmaku();
+    }
+  },
+
+  // 安全初始化丝带
+  safeInitRibbons() {
+    try {
       this.initRibbons();
+    } catch (err) {
+      console.error('初始化丝带失败:', err);
+      this.ribbons = [];
+    }
+  },
+
+  // 安全初始化弹幕
+  safeInitDanmaku() {
+    try {
       this.initDanmaku();
+    } catch (err) {
+      console.error('初始化弹幕失败:', err);
+      this.danmaku = [];
     }
   },
 
@@ -931,7 +951,16 @@ Page({
   // 获取当前树
   getCurrentTree() {
     const { trees, currentTreeIndex } = this.data;
-    return trees[currentTreeIndex] || { type: 'pine' };
+    const tree = trees[currentTreeIndex];
+    // 确保返回有效的树对象，带默认类型
+    if (!tree) {
+      return { type: 'pine', name: '许愿树' };
+    }
+    // 确保有type字段
+    if (!tree.type) {
+      tree.type = 'pine';
+    }
+    return tree;
   },
 
   // 切换树