fix npe

connector/src/main/java/org/geysermc/connector/entity/living/monster/ShulkerEntity.java

@@ -49,8 +49,10 @@ public class ShulkerEntity extends GolemEntity {
         }
         if (entityMetadata.getId() == 16) {
             Position position = (Position) entityMetadata.getValue();
+            if(position != null){
                 metadata.put(EntityData.SHULKER_ATTACH_POS, Vector3i.from(position.getX(), position.getY(), position.getZ()));
             }
+        }
         //TODO Outdated metadata flag SHULKER_PEAK_HEIGHT
 //        if (entityMetadata.getId() == 17) {
 //            int height = (byte) entityMetadata.getValue();