fix unable to attack mounts with no player on them

src/main/java/me/youhavetrouble/preventstabby/PreventStabby.java

@@ -22,9 +22,9 @@ public final class PreventStabby extends JavaPlugin {
 
     @Getter private static PreventStabby plugin;
     private ConfigCache configCache;
-    protected PlayerManager playerManager;
-    protected DatabaseSQLite sqLite;
-    protected SmartCache smartCache;
+    private PlayerManager playerManager;
+    private DatabaseSQLite sqLite;
+    private SmartCache smartCache;
 
     @Override
     public void onEnable() {

src/main/java/me/youhavetrouble/preventstabby/util/Util.java

@@ -52,7 +52,7 @@ public class Util {
                 playerPassengersWithPvpEnabled.add(player.getUniqueId());
         }
 
-        if (playerPassengersWithPvpEnabled.isEmpty()) {
+        if (!mount.getPassengers().isEmpty() && playerPassengersWithPvpEnabled.isEmpty()) {
             PluginMessages.sendActionBar(attacker, config.getCannot_attack_mounts_victim());
             return true;
         }