From 5447561d3d5de42f47c18f91cc473f603beda115 Mon Sep 17 00:00:00 2001
From: fullwall <fullwall25@gamil.com>
Date: Fri, 18 Jan 2019 01:56:47 +0800
Subject: [PATCH] Validate state

---
 main/src/main/java/net/citizensnpcs/Citizens.java | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/main/src/main/java/net/citizensnpcs/Citizens.java b/main/src/main/java/net/citizensnpcs/Citizens.java
index ee62b082e..146058f63 100644
--- a/main/src/main/java/net/citizensnpcs/Citizens.java
+++ b/main/src/main/java/net/citizensnpcs/Citizens.java
@@ -381,9 +381,14 @@ public class Citizens extends JavaPlugin implements CitizensPlugin {
 
     @Override
     public void setDefaultNPCDataStore(NPCDataStore store) {
-        saves.storeAll(npcRegistry);
-        saves.saveToDiskImmediate();
-        despawnNPCs();
+        if (store == null) {
+            throw new IllegalArgumentException("must be non-null");
+        }
+        if (saves != null) {
+            saves.storeAll(npcRegistry);
+            saves.saveToDiskImmediate();
+            despawnNPCs();
+        }
         this.saves = store;
         this.npcRegistry = new CitizensNPCRegistry(saves);
     }