Fix memory leak

main/src/main/java/net/citizensnpcs/EventListen.java

@@ -305,6 +305,7 @@ public class EventListen implements Listener {
         int delay = npc.data().get(NPC.RESPAWN_DELAY_METADATA, -1);
         if (delay < 0)
             return;
+        int deathAnimationTicks = event.getEntity() instanceof LivingEntity ? 10 : 2;
         Bukkit.getScheduler().scheduleSyncDelayedTask(CitizensAPI.getPlugin(), new Runnable() {
             @Override
             public void run() {
@@ -312,7 +313,7 @@ public class EventListen implements Listener {
                     npc.spawn(location, SpawnReason.TIMED_RESPAWN);
                 }
             }
-        }, delay + 2);
+        }, delay + deathAnimationTicks);
     }
 
     @EventHandler

main/src/main/java/net/citizensnpcs/npc/CitizensNPCRegistry.java

@@ -156,7 +156,30 @@ public class CitizensNPCRegistry implements NPCRegistry {
 
     @Override
     public Iterator<NPC> iterator() {
-        return npcs.valueCollection().iterator();
+        return new Iterator<NPC>() {
+            Iterator<NPC> itr = npcs.valueCollection().iterator();
+            NPC npc;
+
+            @Override
+            public boolean hasNext() {
+                return itr.hasNext();
+            }
+
+            @Override
+            public NPC next() {
+                npc = itr.next();
+                return npc;
+            }
+
+            @Override
+            public void remove() {
+                itr.remove();
+                if (npc != null) {
+                    uniqueNPCs.remove(npc.getUniqueId());
+                    npc = null;
+                }
+            }
+        };
     }
 
     @Override