received an unhandled rejection TypeError after update to "hexo": "^3.1.0"

[PokimLee]

Unhandled rejection TypeError: /Users/pokim/Project/hexoFolder/themes/huno/layout/layout.ejs:6
4|
5|
6| <%
7| var title = page.title;
8| var description = page.description || '';
9|

Cannot read property 'substring' of null
at eval (eval at (/Users/pokim/Project/hexoFolder/node_modules/hexo-renderer-ejs/node_modules/ejs/lib/ejs.js:242:14), :66:30)
at eval (eval at (/Users/pokim/Project/hexoFolder/node_modules/hexo-renderer-ejs/node_modules/ejs/lib/ejs.js:242:14), :67:4294)
at /Users/pokim/Project/hexoFolder/node_modules/hexo-renderer-ejs/node_modules/ejs/lib/ejs.js:255:15
at Object.exports.render (/Users/pokim/Project/hexoFolder/node_modules/hexo-renderer-ejs/node_modules/ejs/lib/ejs.js:293:13)
at Hexo. (/Users/pokim/Project/hexoFolder/node_modules/hexo-renderer-ejs/index.js:5:14)
at Hexo.tryCatcher (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/util.js:26:23)
at Hexo. (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/method.js:15:34)
at /Users/pokim/Project/hexoFolder/node_modules/hexo/lib/hexo/render.js:51:21
at tryCatcher (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/util.js:26:23)
at Promise._settlePromiseFromHandler (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/promise.js:503:31)
at Promise._settlePromiseAt (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/promise.js:577:18)
at Promise._settlePromiseAtPostResolution (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/promise.js:244:10)
at Async._drainQueue (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/async.js:128:12)
at Async._drainQueues (/Users/pokim/Project/hexoFolder/node_modules/hexo/node_modules/bluebird/js/main/async.js:133:10)
at Immediate.Async.drainQueues as _onImmediate
at processImmediate as _immediateCallback

[letiantian]

title or description may not have been defined in hexo's config file.

[PokimLee]

@someus problem solved! thx