fix: return null if reference is null

generated_world/src/main/java/mc/world/generated_world/chunk/ChunkImpl.java

@@ -112,7 +112,7 @@ public class ChunkImpl implements Chunk{
     @Override
     public Region getRegion() {
         if (region == null) {
-            throw new IllegalStateException("Region is not initialized");
+            return null;
         }
         if (region.get() == null) {
             throw new ResourceUnloadedException("Region is unloaded");

generated_world/src/main/java/mc/world/generated_world/region/RegionImpl.java

@@ -81,7 +81,7 @@ public class RegionImpl implements Region{
     @Override
     public World getWorld() {
         if (world == null) {
-            throw new IllegalStateException("World is not initialized");
+            return null;
         }
         if (world.get() == null) {
             throw new ResourceUnloadedException("World is unloaded");