Checking on unloading

core/src/main/java/mc/core/Location.java

@@ -5,15 +5,17 @@
 package mc.core;
 
 import lombok.Data;
+import mc.core.exception.ResourceUnloadException;
 import mc.core.world.World;
 
 import java.io.Serializable;
+import java.lang.ref.Reference;
 import java.lang.ref.WeakReference;
 
 @Data
 public class Location implements Serializable{
     private double x, y, z;
-    private WeakReference<World> world;
+    private Reference<World> world;
 
     private static int floor_double(double value) {
         int i = (int)value;
@@ -53,6 +55,7 @@ public class Location implements Serializable{
 
     public Location(long compactValue, World world) {
         set(compactValue);
+        this.world = new WeakReference<>(world);
     }
 
     public void set(Location location) {
@@ -95,6 +98,9 @@ public class Location implements Serializable{
     }
 
     public World getWorld () {
+        if (world.get() == null) {
+            throw new ResourceUnloadException("You're trying to get unloaded world");
+        }
         return this.world.get();
     }
 

core/src/main/java/mc/core/exception/McCoreUncheckedException.java

@@ -0,0 +1,12 @@
+package mc.core.exception;
+
+public abstract class McCoreUncheckedException extends RuntimeException {
+
+    public McCoreUncheckedException() {
+        super();
+    }
+
+    public McCoreUncheckedException(String msg) {
+        super(msg);
+    }
+}

core/src/main/java/mc/core/exception/ResourceUnloadException.java

@@ -0,0 +1,8 @@
+package mc.core.exception;
+
+public class ResourceUnloadException extends McCoreUncheckedException {
+
+    public ResourceUnloadException(String msg) {
+        super(msg);
+    }
+}