add a simple guard against unparsed messages when trimming history

lib/storage/file.js

@@ -970,6 +970,15 @@ var trimChannel = function (env, channelName, hash, _cb) {
             }
 
             var msg = Util.tryParse(s_msg);
+
+            if (!msg) {
+                Log.error("TRIM_HISTORY_UNPARSED_LINE", {
+                    content: s_msg,
+                    index: i,
+                });
+                return void readMore();
+            }
+
             var msgHash = Extras.getHash(msg[4]);
 
             if (msgHash === hash) {