Hotfix RegionedBossbar

Signed-off-by: yoyosource <yoyosource@nidido.de>

BauSystem_Main/src/de/steamwar/bausystem/utils/bossbar/RegionedBossbar.java

@@ -135,8 +135,10 @@ public class RegionedBossbar implements BauSystemBossbar, Listener {
 
     @Override
     public void cleanup() {
-        bossBar.removeAll();
-        bossBar = null;
+        if (bossBar != null) {
+            bossBar.removeAll();
+            bossBar = null;
+        }
         region = null;
         player = null;