Defensive code to prevent nether border if it doesn't need one.

Author: tastybento

src/main/java/world/bentobox/border/listeners/ShowVirtualWorldBorder.java

@@ -35,7 +35,11 @@ public void showBorder(Player player, Island island) {
                 || !Objects.requireNonNull(User.getInstance(player)).getMetaData(BORDER_STATE_META_DATA).map(MetaDataValue::asBoolean).orElse(addon.getSettings().isShowByDefault())) {
             return;
         }
-        Location l = island.getProtectionCenter();
+        
+        if (player.getWorld().getEnvironment() == Environment.NETHER && !addon.getPlugin().getIWM().isIslandNether(player.getWorld())) {
+            return;
+        }
+        Location l = island.getProtectionCenter().toVector().toLocation(player.getWorld());
         if (player.getWorld().getEnvironment() == Environment.NETHER) {
             l.multiply(8);
         }

src/test/java/world/bentobox/border/listeners/ShowVirtualWorldBorderTest.java

@@ -8,6 +8,7 @@
 import org.bukkit.Bukkit;
 import org.bukkit.WorldBorder;
 import org.bukkit.entity.Player;
+import org.bukkit.util.Vector;
 import org.eclipse.jdt.annotation.NonNull;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -50,11 +51,13 @@ public void setUp() throws Exception {
         // Island
         when(island.getRange()).thenReturn(400);
         when(island.getProtectionRange()).thenReturn(100);
+        when(island.getProtectionCenter()).thenReturn(location);
 
         // User
         MockedStatic<User> mockedUser = Mockito.mockStatic(User.class, Mockito.RETURNS_MOCKS);
         mockedUser.when(() -> User.getInstance(any(Player.class))).thenReturn(user);
         when(user.getPlayer()).thenReturn(mockPlayer);
+        when(location.toVector()).thenReturn(new Vector(0,0,0));
         when(mockPlayer.getLocation()).thenReturn(location);
         when(mockPlayer.getWorld()).thenReturn(world);