解决搜索降级bug

@@ -150,7 +150,7 @@ const index = (req, res, next) => {
             }),
             pageFooter: true,
             search: {
-                defaultTerms: (result.defaultTerms.length !== 0) ? result.defaultTerms[0].content : '',
+                defaultTerms: (result.length && result.defaultTerms && result.defaultTerms.length !== 0) ? result.defaultTerms[0].content : '',
                 url: helpers.urlFormat('', null, 'search'),
                 hotTerms: result.hotTerms
             }