From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 23 Apr 2020 01:36:39 -0400
Subject: [PATCH] Don't fire BlockFade on worldgen threads

Caused a deadlock

diff --git a/src/main/java/net/minecraft/world/level/block/FireBlock.java b/src/main/java/net/minecraft/world/level/block/FireBlock.java
index 31b6c1333c7d0af28385e804e94348cef398748b..ac63c5bef5b35b158e57835d765bbdd15fc60664 100644
--- a/src/main/java/net/minecraft/world/level/block/FireBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/FireBlock.java
@@ -93,6 +93,7 @@ public class FireBlock extends BaseFireBlock {
     @Override
     public BlockState updateShape(BlockState state, Direction direction, BlockState newState, LevelAccessor world, BlockPos pos, BlockPos posFrom) {
         // CraftBukkit start
+        if (!(world instanceof ServerLevel)) return this.canSurvive(state, world, pos) ? (BlockState) this.getStateWithAge(world, pos, (Integer) state.getValue(FireBlock.AGE)) : Blocks.AIR.defaultBlockState(); // Paper - don't fire events in world generation
         if (!this.canSurvive(state, world, pos)) {
             // Suppress during worldgen
             if (!(world instanceof Level)) {
@@ -108,7 +109,7 @@ public class FireBlock extends BaseFireBlock {
                 return blockState.getHandle();
             }
         }
-        return this.getStateWithAge(world, pos, (Integer) state.getValue(FireBlock.AGE));
+        return this.getStateWithAge(world, pos, (Integer) state.getValue(FireBlock.AGE)); // Paper - diff on change, see "don't fire events in world generation"
         // CraftBukkit end
     }