fix post?.

themes/medium/components/BlogPostListScroll.js

@@ -20,7 +20,7 @@ const BlogPostListScroll = ({ posts = [], currentSearch }) => {
   const searchKey = getSearchKey()
   if (searchKey) {
     filteredPosts = posts.filter(post => {
-      const tagContent = post.tags ? post.tags.join(' ') : ''
+      const tagContent = post?.tags ? post?.tags.join(' ') : ''
       const searchContent = post.title + post.summary + tagContent
       return searchContent.toLowerCase().includes(searchKey.toLowerCase())
     })

themes/medium/index.js

@@ -174,7 +174,7 @@ const LayoutSlug = props => {
                         </div>
                     </div>
                     {/* 上一篇下一篇文章 */}
-                    {post.type === 'Post' && <ArticleAround prev={prev} next={next} />}
+                    {post?.type === 'Post' && <ArticleAround prev={prev} next={next} />}
                     {/* 评论区 */}
                     <Comment frontMatter={post} />
                 </section>