Null check max status in GenerationChunkHolder#getChunkIfPresent

If the ticket level is set to unloaded, then it will be null.

src/main/java/ca/spottedleaf/moonrise/mixin/chunk_system/GenerationChunkHolderMixin.java

@@ -226,7 +226,7 @@ public abstract class GenerationChunkHolderMixin {
     public ChunkAccess getChunkIfPresent(final ChunkStatus chunkStatus) {
         final ChunkStatus maxStatus = ChunkLevel.generationStatus(this.getTicketLevel());
 
-        if (chunkStatus.isOrAfter(maxStatus)) {
+        if (maxStatus == null || chunkStatus.isOrAfter(maxStatus)) {
             return null;
         }