From ff5ccababd1855ad5314d8fda45a4c22a900d942 Mon Sep 17 00:00:00 2001
From: Querz <info@querz.net>
Date: Mon, 24 Jun 2019 19:59:46 +0200
Subject: [PATCH] handle empty sections

---
 src/main/java/net/querz/nbt/mca/Chunk.java   | 10 +++++++++-
 src/main/java/net/querz/nbt/mca/Section.java | 12 ++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/main/java/net/querz/nbt/mca/Chunk.java b/src/main/java/net/querz/nbt/mca/Chunk.java
index 3f0ae94d..cd53152a 100644
--- a/src/main/java/net/querz/nbt/mca/Chunk.java
+++ b/src/main/java/net/querz/nbt/mca/Chunk.java
@@ -73,7 +73,15 @@ private void initReferences() {
 		this.structures = level.getCompoundTag("Structures");
 		if (level.containsKey("Sections")) {
 			for (CompoundTag section : level.getListTag("Sections").asCompoundTagList()) {
-				this.sections[section.getByte("Y")] = new Section(section);
+				int sectionIndex = section.getByte("Y");
+				if (sectionIndex > 15 || sectionIndex < 0) {
+					continue;
+				}
+				Section newSection = new Section(section);
+				if (newSection.isEmpty()) {
+					continue;
+				}
+				this.sections[sectionIndex] = newSection;
 			}
 		}
 	}
diff --git a/src/main/java/net/querz/nbt/mca/Section.java b/src/main/java/net/querz/nbt/mca/Section.java
index e94ea164..0ec467f6 100644
--- a/src/main/java/net/querz/nbt/mca/Section.java
+++ b/src/main/java/net/querz/nbt/mca/Section.java
@@ -17,8 +17,11 @@ public class Section {
 	private byte[] skyLight;
 
 	public Section(CompoundTag sectionRoot) {
-		data = sectionRoot;
-		palette = sectionRoot.getListTag("Palette").asCompoundTagList();
+		ListTag<?> rawPalette = sectionRoot.getListTag("Palette");
+		if (rawPalette == null) {
+			return;
+		}
+		palette = rawPalette.asCompoundTagList();
 		for (int i = 0; i < palette.size(); i++) {
 			CompoundTag data = palette.get(i);
 			putValueIndexedPalette(data, i);
@@ -26,6 +29,7 @@ public Section(CompoundTag sectionRoot) {
 		blockLight = sectionRoot.getByteArray("BlockLight");
 		blockStates = sectionRoot.getLongArray("BlockStates");
 		skyLight = sectionRoot.getByteArray("SkyLight");
+		data = sectionRoot;
 	}
 
 	Section() {}
@@ -72,6 +76,10 @@ private class PaletteIndex {
 		}
 	}
 
+	public boolean isEmpty() {
+		return data == null;
+	}
+
 	public CompoundTag getBlockStateAt(int blockX, int blockY, int blockZ) {
 		int index = getBlockIndex(blockX, blockY, blockZ);
 		int paletteIndex = getPaletteIndex(index);