message: Use appropriate Member object when rendering thread summary
diff: @@ -90,17 +90,16 @@ export const ThreadMessagePreview = ({ thread, showDisplayname = false }: IPrevi
  }, [lastReply, replacingEventId]);
  if (!preview) return null;
  - const sender = thread.roomState.getSentinelMember(lastReply.getSender());
  return <>
  <MemberAvatar
  - member={sender}
  + member={lastReply.sender}
  fallbackUserId={lastReply.getSender()}
  width={24}
  height={24}
  className="mx_ThreadInfo_avatar"
  />
  { showDisplayname && <div className="mx_ThreadInfo_sender">
  - { sender?.name ?? lastReply.getSender() }
  + { lastReply.sender?.name ?? lastReply.getSender() }
  </div> }
  <div className="mx_ThreadInfo_content">
  <span className="mx_ThreadInfo_message-preview">
  