Hotfix TypeMappers

src/de/steamwar/bungeecore/commands/TypeMappers.java

@@ -66,6 +66,12 @@ public class TypeMappers {
                 return ArenaMode.getByChat(s);
             }
 
+            @Override
+            public boolean validate(CommandSender sender, ArenaMode value, MessageSender messageSender) {
+                if (value == null) return true;
+                return value.isHistoric() == historic;
+            }
+
             @Override
             public Collection<String> tabCompletes(CommandSender sender, String[] previousArguments, String s) {
                 return ArenaMode.getAllChatNames(historic);