Bug: Errors when footnote in citation/当在引用中添加脚注时报错 #21
Description
在我在引用之中添加脚注，会在生成时报错：
INFO Start processing
FATAL {
err: TypeError: Cannot read properties of undefined (reading 'content')
at D:\Code\Quasimoodo.github.io\node_modules\hexo-reference\src\footnotes.js:55:43
at String.replace ()
at renderFootnotes (D:\Code\Quasimoodo.github.io\node_modules\hexo-reference\src\footnotes.js:53:17)
at Hexo. (D:\Code\Quasimoodo.github.io\node_modules\hexo-reference\index.js:6:18)
at Hexo.tryCatcher (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\util.js:16:23)
at Hexo. (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\method.js:15:34)
at D:\Code\Quasimoodo.github.io\node_modules\hexo\lib\extend\filter.js:67:52
at tryCatcher (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\util.js:16:23)
at Object.gotValue (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\reduce.js:166:18)
at Object.gotAccum (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\reduce.js:155:25)
at Object.tryCatcher (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\util.js:16:23)
at Promise._settlePromiseFromHandler (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\promise.js:547:31)
at Promise._settlePromise (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\promise.js:604:18)
at Promise._settlePromise0 (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\promise.js:649:10)
at Promise._settlePromises (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\promise.js:729:18)
at _drainQueueStep (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\async.js:93:12)
at _drainQueue (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\async.js:86:9)
at Async._drainQueues (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\async.js:102:5)
at Async.drainQueues [as _onImmediate] (D:\Code\Quasimoodo.github.io\node_modules\bluebird\js\release\async.js:15:14)
at process.processImmediate (node:internal/timers:471:21)
} Something's wrong. Maybe you can find the solution here: %s https://hexo.io/docs/troubleshooting.html
复现代码如图，在typora中可以正常渲染：
