don't hang when reading unparseable lines from history

lib/historyKeeper.js

@@ -595,7 +595,9 @@ module.exports.create = function (cfg, cb) {
             const start = (beforeHash) ? 0 : offset;
             store.readMessagesBin(channelName, start, (msgObj, readMore, abort) => {
                 if (beforeHash && msgObj.offset >= offset) { return void abort(); }
-                handler(tryParse(msgObj.buff.toString('utf8')), readMore);
+                var parsed = tryParse(msgObj.buff.toString('utf8'));
+                if (!parsed) { return void readMore(); }
+                handler(parsed, readMore);
             }, waitFor(function (err) {
                 return void cb(err);
             }));
@@ -747,7 +749,6 @@ module.exports.create = function (cfg, cb) {
 
             // TODO compute lastKnownHash in a manner such that it will always skip past the metadata line?
             getHistoryAsync(channelName, lastKnownHash, false, (msg, readMore) => {
-                if (!msg) { return; } // XXX
                 msgCount++;
                 // avoid sending the metadata message a second time
                 if (isMetadataMessage(msg) && metadata_cache[channelName]) { return readMore(); }
@@ -866,7 +867,6 @@ module.exports.create = function (cfg, cb) {
         // FIXME should we send metadata here too?
         // none of the clientside code which uses this API needs metadata, but it won't hurt to send it (2019-08-22)
         return void getHistoryAsync(parsed[1], -1, false, (msg, readMore) => {
-            if (!msg) { return; }
             Server.send(userId, [0, HISTORY_KEEPER_ID, 'MSG', userId, JSON.stringify(['FULL_HISTORY', msg])], readMore);
         }, (err) => {
             let parsedMsg = ['FULL_HISTORY_END', parsed[1]];