fix: don't crash if post is undefined

src/posts/index.js

@@ -93,7 +93,7 @@ Posts.getPostIndices = async function (posts, uid) {
 };
 
 Posts.modifyPostByPrivilege = function (post, privileges) {
-	if (post.deleted && !(post.selfPost || privileges['posts:view_deleted'])) {
+	if (post && post.deleted && !(post.selfPost || privileges['posts:view_deleted'])) {
 		post.content = '[[topic:post_is_deleted]]';
 		if (post.user) {
 			post.user.signature = '';