fixed 删除用户时issue，pr，评论用户显示已注销

app/views/journals/_journal_item.json.jbuilder

@@ -1,7 +1,7 @@
 json.id journal.id
-json.user_name journal.user.try(:show_real_name)
-json.user_login journal.user.try(:login)
-json.user_picture url_to_avatar(journal.user)
+json.user_name journal.user.blank?? "已注销": journal.user.show_real_name
+json.user_login journal.user&.login
+json.user_picture journal.user.blank?? User::Avatar.get_letter_avatar_url("D") : url_to_avatar(journal.user)
 json.is_journal_detail journal.is_journal_detail?  #判断是否修改了参数而添加的回复内容
 json.content journal.try(:notes)
 json.journal_details journal.journal_content