nullability checks (#200)

common/src/main/java/com/hibiscusmc/hmccosmetics/cosmetic/types/CosmeticBackpackType.java

@@ -109,6 +109,7 @@ public class CosmeticBackpackType extends Cosmetic implements CosmeticUpdateBeha
         if(backpackManager == null) return;
 
         UserEntity entityManager = backpackManager.getEntityManager();
+        if(entityManager == null) return;
 
         entityManager.teleport(loc);
         entityManager.setRotation((int) loc.getYaw(), isFirstPersonCompadible());

common/src/main/java/com/hibiscusmc/hmccosmetics/user/CosmeticUser.java

@@ -54,7 +54,7 @@ public class CosmeticUser implements CosmeticHolder {
     private final HashMap<CosmeticSlot, Cosmetic> playerCosmetics = new HashMap<>();
     private UserWardrobeManager userWardrobeManager;
     private UserBalloonManager userBalloonManager;
-    @Getter
+    @Getter @Nullable
     private UserBackpackManager userBackpackManager;
 
     // Cosmetic Settings/Toggles

common/src/main/java/com/hibiscusmc/hmccosmetics/user/manager/UserBackpackManager.java

@@ -16,6 +16,7 @@ import org.bukkit.entity.EntityType;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.EquipmentSlot;
 import org.bukkit.inventory.ItemStack;
+import org.jspecify.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -30,7 +31,7 @@ public class UserBackpackManager {
     private ArrayList<Integer> particleCloud = new ArrayList<>();
     @Getter
     private final CosmeticUser user;
-    @Getter
+    @Getter @Nullable
     private UserEntity entityManager;
 
     public UserBackpackManager(CosmeticUser user) {