Handle bad chunks more gracefully

Brought this patch back from the graveyard, 1.13.x changed how chunks
where loaded and the patch was dropped.

Prior to this change the server would crash when attempting to load a
chunk from a region with bad data.

After this change the server will defer back to vanilla behavior. At
this time, that means attempting to generate a chunk in its place
(and occasionally just not generating anything and leaving small
holes in the world (This might not be accurate as of 1.13.x)).

Should Mojang choose to alter this behavior in the future, this change
will simply defer to whatever that new behavior is.

Spigot-Server-Patches/0438-Handle-bad-chunks-more-gracefully.patch

@@ -0,0 +1,60 @@
+From a5bd0235ffaaae6207d3ac887c2b8ccc2b60d39d Mon Sep 17 00:00:00 2001
+From: Shane Freeder <theboyetronic@gmail.com>
+Date: Mon, 15 Apr 2019 02:24:52 +0100
+Subject: [PATCH] Handle bad chunks more gracefully
+
+Prior to this change the server would crash when attempting to load a
+chunk from a region with bad data.
+
+After this change the server will defer back to vanilla behavior. At
+this time, that means attempting to generate a chunk in its place
+(and occasionally just not generating anything and leaving small
+holes in the world (This statement might not be accurate as of 1.13.x)).
+
+Should Mojang choose to alter this behavior in the future, this change
+will simply defer to whatever that new behavior is.
+
+diff --git a/src/main/java/net/minecraft/server/RegionFileCache.java b/src/main/java/net/minecraft/server/RegionFileCache.java
+index 17e76815ad..2eb7888027 100644
+--- a/src/main/java/net/minecraft/server/RegionFileCache.java
++++ b/src/main/java/net/minecraft/server/RegionFileCache.java
+@@ -171,8 +171,20 @@ public class RegionFileCache {
+     private static NBTTagCompound readOversizedChunk(RegionFile regionfile, int i, int j) throws IOException {
+         synchronized (regionfile) {
+             try (DataInputStream datainputstream = regionfile.getReadStream(i & 31, j & 31)) {
++                // Paper start - Handle bad chunks more gracefully - also handle similarly with oversized data
+                 NBTTagCompound oversizedData = regionfile.getOversizedData(i, j);
+-                NBTTagCompound chunk = NBTCompressedStreamTools.readNBT(datainputstream);
++
++                try {
++                    oversizedData = regionfile.getOversizedData(i, j);
++                } catch (Exception ex) {}
++
++                NBTTagCompound chunk;
++                try {
++                     chunk = NBTCompressedStreamTools.readNBT(datainputstream);
++                } catch (Exception ex) {
++                    return null;
++                }
++                // Paper end
+                 if (oversizedData == null) {
+                     return chunk;
+                 }
+@@ -251,7 +263,13 @@ public class RegionFileCache {
+             return null;
+         }
+ 
+-        return NBTCompressedStreamTools.a(datainputstream);
++        // Paper start - Handle bad chunks more gracefully
++        try {
++            return NBTCompressedStreamTools.a(datainputstream);
++        } catch (Exception ex) {
++            return null;
++        }
++        // Paper end
+     }
+ 
+     @Nullable
+-- 
+2.21.0
+