评论验证码取不到时降级为可重试提示（不留破图）

themes/Ying/layouts/page/comment.html

@@ -283,7 +283,22 @@
       '<button class="atk-human-btn" type="button">确认</button>';
     var img = w.querySelector('.atk-human-img');
     var inp = w.querySelector('.atk-human-inp');
-    function refresh() { api('/captcha').then(function (c) { if (c && c.img_data) img.src = c.img_data; }); }
+    function refresh() {
+      img.style.display = '';
+      api('/captcha').then(function (c) {
+        if (c && c.img_data) { img.src = c.img_data; }
+        else { fail('验证码暂时取不到'); }
+      }).catch(function () { fail('验证码暂时取不到'); });
+    }
+    // 图形验证码取不到（接口抖动/数据库不可用）时给个可重试的提示，别留一张破图
+    function fail(msg) {
+      img.style.display = 'none';
+      var t = w.querySelector('.atk-human-box-tx');
+      if (t) { t.innerHTML = msg + '，<b style="cursor:pointer;text-decoration:underline">点这里重试</b>'; }
+    }
+    w.addEventListener('click', function (e) {
+      if (e.target && e.target.tagName === 'B') refresh();
+    });
     refresh();
     img.onclick = refresh;
     function submit() {