fixed NPE when interacting with NPC's

src/main/java/net/Indyuce/mmocore/api/player/PlayerData.java

@@ -883,6 +883,22 @@ public class PlayerData extends OfflinePlayerData {
         return MMOCore.plugin.dataProvider.getDataManager().get(uuid);
     }
 
+    /**
+     * This is used to check if the player data is loaded for a
+     * specific player. This might seem redundant because the given
+     * Player instance is linked to an online player, and data
+     * is always loaded for an online player.
+     * <p>
+     * In fact a Player instance can be attached to a Citizens NPC
+     * which has no player data loaded hence this method
+     *
+     * @param player Either a real player or an NPC
+     * @return If player data for that player is loaded
+     */
+    public static boolean has(Player player) {
+        return MMOCore.plugin.dataProvider.getDataManager().isLoaded(player.getUniqueId());
+    }
+
     public static Collection<PlayerData> getAll() {
         return MMOCore.plugin.dataProvider.getDataManager().getLoaded();
     }

src/main/java/net/Indyuce/mmocore/comp/MMOCoreTargetRestriction.java

@@ -11,7 +11,7 @@ public class MMOCoreTargetRestriction implements TargetRestriction {
     @Override
     public boolean canTarget(Player player, LivingEntity target, InteractionType interaction) {
 
-        if (interaction.isOffense() && target instanceof Player) {
+        if (interaction.isOffense() && target instanceof Player && PlayerData.has((Player) target)) {
             PlayerData targetData = PlayerData.get(target.getUniqueId());
 
             // Check for the same party