Fix NPE on /addxp

src/main/java/com/gmail/nossr50/commands/experience/ExperienceCommand.java

@@ -67,7 +67,7 @@ public abstract class ExperienceCommand implements TabExecutor {
                 }
 
                 String playerName = Misc.getMatchedPlayerName(args[0]);
-                McMMOPlayer mcMMOPlayer = UserManager.getPlayer(playerName, true);
+                mcMMOPlayer = UserManager.getPlayer(playerName, true);
 
                 // If the mcMMOPlayer doesn't exist, create a temporary profile and check if it's present in the database. If it's not, abort the process.
                 if (mcMMOPlayer == null) {