leave a FIXME in the server

lib/hk-util.js

@@ -677,6 +677,7 @@ const handleGetHistory = function (Env, Server, seq, userId, parsed) {
                     err: err && err.message || err,
                     stack: err && err.stack,
                 }); }
+                // FIXME err.message isn't useful for users
                 const parsedMsg = {error:err.message, channel: channelName, txid: txid};
                 Server.send(userId, [0, HISTORY_KEEPER_ID, 'MSG', userId, JSON.stringify(parsedMsg)]);
                 return;