Fix SubCommand.getGuardChecker

SpigotCore_Main/src/de/steamwar/command/SubCommand.java

@@ -101,7 +101,7 @@ class SubCommand {
                 return localGuardChecker.getOrDefault(s, GUARD_FUNCTIONS.getOrDefault(s, null));
             }
             GuardChecker current = localGuardChecker.getOrDefault(guard.value(), GUARD_FUNCTIONS.getOrDefault(guard.value(), null));
-            if (guardChecker == null) {
+            if (current == null) {
                 Bukkit.getLogger().log(Level.WARNING, () -> "The guard checker with name '" + guard.value() + "' is neither a local guard checker nor a global one");
             }
             return current;