Do not sync load chunk for dynamic game event listener registration

These can be called while an entity is being added to the world,
and if the entity is being added from a chunk load context the
sync load will block indefinitely (because the chunk load context
is for completing the chunk to FULL).

This does raise questions about the current system for these
dynamic registrations, as it looks like there is _zero_ logic
to account for the case where the chunk is _not_ currently loaded
and then later loaded.

patches/server/0921-Do-not-sync-load-chunk-for-dynamic-game-event-listen.patch

@@ -0,0 +1,29 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Spottedleaf <Spottedleaf@users.noreply.github.com>
+Date: Sun, 3 Jul 2022 22:31:37 -0700
+Subject: [PATCH] Do not sync load chunk for dynamic game event listener
+ registration
+
+These can be called while an entity is being added to the world,
+and if the entity is being added from a chunk load context the
+sync load will block indefinitely (because the chunk load context
+is for completing the chunk to FULL).
+
+This does raise questions about the current system for these
+dynamic registrations, as it looks like there is _zero_ logic
+to account for the case where the chunk is _not_ currently loaded
+and then later loaded.
+
+diff --git a/src/main/java/net/minecraft/world/level/gameevent/DynamicGameEventListener.java b/src/main/java/net/minecraft/world/level/gameevent/DynamicGameEventListener.java
+index 39f79c6d95e0f14d55783375df9ecf053e8d19de..610bfcceec51fcd1d82040f0dbfc03be20b8dce7 100644
+--- a/src/main/java/net/minecraft/world/level/gameevent/DynamicGameEventListener.java
++++ b/src/main/java/net/minecraft/world/level/gameevent/DynamicGameEventListener.java
+@@ -66,7 +66,7 @@ public class DynamicGameEventListener<T extends GameEventListener> {
+ 
+     private static void ifChunkExists(LevelReader world, @Nullable SectionPos sectionPos, Consumer<GameEventDispatcher> dispatcherConsumer) {
+         if (sectionPos != null) {
+-            ChunkAccess chunkAccess = world.getChunk(sectionPos.x(), sectionPos.z(), ChunkStatus.FULL, false);
++            ChunkAccess chunkAccess = world.getChunkIfLoadedImmediately(sectionPos.getX(), sectionPos.getZ()); // Paper - can cause sync loads while completing a chunk, resulting in deadlock
+             if (chunkAccess != null) {
+                 dispatcherConsumer.accept(chunkAccess.getEventDispatcher(sectionPos.y()));
+             }