SPIGOT-6076: Crash when updating blocks in uninitialized chunk sections

By: md_5 <git@md-5.net>

paper-server/nms-patches/PacketPlayOutMultiBlockChange.patch

@@ -0,0 +1,11 @@
+--- a/net/minecraft/server/PacketPlayOutMultiBlockChange.java
++++ b/net/minecraft/server/PacketPlayOutMultiBlockChange.java
+@@ -24,7 +24,7 @@
+             short short0 = (Short) shortiterator.next();
+ 
+             this.b[i] = short0;
+-            this.c[i] = chunksection.getType(SectionPosition.a(short0), SectionPosition.b(short0), SectionPosition.c(short0));
++            this.c[i] = (chunksection != null) ? chunksection.getType(SectionPosition.a(short0), SectionPosition.b(short0), SectionPosition.c(short0)) : Blocks.AIR.getBlockData(); // CraftBukkit - SPIGOT-6076, Mojang bug when empty chunk section notified
+         }
+ 
+     }