Tree & Breadcrumb: fix setAttribute to undefined bug

packages/breadcrumb/src/breadcrumb.vue

@@ -26,7 +26,9 @@
 
     mounted() {
       const items = this.$el.querySelectorAll('.el-breadcrumb__item');
-      items[items.length - 1].setAttribute('aria-current', 'page');
+      if (items.length) {
+        items[items.length - 1].setAttribute('aria-current', 'page');
+      }
     }
   };
 </script>

packages/tree/src/tree.vue

@@ -194,7 +194,7 @@
           checkedItem[0].setAttribute('tabindex', 0);
           return;
         }
-        this.treeItems[0].setAttribute('tabindex', 0);
+        this.treeItems[0] && this.treeItems[0].setAttribute('tabindex', 0);
       },
       handelKeydown(ev) {
         const currentItem = ev.target;