fix potential NPE

Author: HSGamer

src/main/java/me/hsgamer/bettergui/argument/type/PlayerArgumentProcessor.java

@@ -29,7 +29,7 @@ protected Optional<OfflinePlayer> getObject(String name) {
       return Optional.ofNullable(Bukkit.getPlayer(name));
     } else {
       //noinspection deprecation
-      return Optional.ofNullable(Bukkit.getOfflinePlayer(name));
+      return Optional.of(Bukkit.getOfflinePlayer(name));
     }
   }
 

src/main/java/me/hsgamer/bettergui/menu/BaseInventoryMenu.java

@@ -308,7 +308,7 @@ protected void onClose(InventoryCloseEvent event) {
         SchedulerUtil.async().run(batchRunnable);
       }
 
-      if (!closeRequirementApplier.isEmpty()) {
+      if (closeRequirementApplier != null && !closeRequirementApplier.isEmpty()) {
         if (forceClose.contains(uuid)) {
           forceClose.remove(uuid);
           return;

src/main/java/me/hsgamer/bettergui/menu/BaseMenu.java

@@ -116,7 +116,7 @@ public boolean create(Player player, String[] args, boolean bypass) {
     }
 
     // Check Requirement
-    if (!bypass) {
+    if (!bypass && viewRequirementApplier != null && !viewRequirementApplier.isEmpty()) {
       Requirement.Result result = viewRequirementApplier.getResult(uuid);
 
       BatchRunnable batchRunnable = new BatchRunnable();