Prevent error if queue command is used while not in a channel.

src/main/java/moe/nekojimi/chords/commands/QueueCommand.java

@@ -36,7 +36,9 @@ public class QueueCommand extends Command
         String message = ">>> ";
         int i = 1;
 
-        final Track currentTrack = bot.getMusicHandler().getCurrentTrack();
+        Track currentTrack = null;
+        if (bot.getMusicHandler() != null)
+            currentTrack = bot.getMusicHandler().getCurrentTrack();
         if (currentTrack != null)
             message += ":notes: **Now playing: " + currentTrack + "**\n";
         else