Force close world loading screen on join (#7529)

Fixes infinite loading screens for dead players due to async chunk loading and player chunk loading patches and prevents players from missing messages and similar if chunk loading is slow

patches/server/0877-Force-close-world-loading-screen.patch

@@ -0,0 +1,29 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Nassim Jahnke <jahnke.nassim@gmail.com>
+Date: Wed, 2 Mar 2022 09:45:56 +0100
+Subject: [PATCH] Force close world loading screen
+
+Dead players would be stuck in the world loading screen and other players may
+miss messages and similar sent in the join event if chunk loading is slow.
+Paper already circumvents falling through the world before chunks are loaded,
+so we do not need that. The client only needs the chunk it is currently in to
+be loaded to close the loading screen, so we just send an empty one.
+
+diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
+index f5852341161b0d632e22af9b3e625ca1e786bd63..02dc93c394d37c9a84aa4a58d80615c403c54fb9 100644
+--- a/src/main/java/net/minecraft/server/players/PlayerList.java
++++ b/src/main/java/net/minecraft/server/players/PlayerList.java
+@@ -422,6 +422,13 @@ public abstract class PlayerList {
+ 
+         // Paper start - move vehicle into method so it can be called above - short circuit around that code
+         onPlayerJoinFinish(player, worldserver1, s1);
++        // Send empty chunk, so players aren't stuck in the world loading screen
++        net.minecraft.core.Holder<net.minecraft.world.level.biome.Biome> plains = worldserver1.registryAccess().registryOrThrow(net.minecraft.core.Registry.BIOME_REGISTRY)
++            .getHolderOrThrow(net.minecraft.world.level.biome.Biomes.PLAINS);
++        player.connection.send(new net.minecraft.network.protocol.game.ClientboundLevelChunkWithLightPacket(
++            new net.minecraft.world.level.chunk.EmptyLevelChunk(worldserver1, player.chunkPosition(), plains),
++            worldserver1.getLightEngine(), null, null, true, false)
++        );
+     }
+     private void mountSavedVehicle(ServerPlayer player, ServerLevel worldserver1, CompoundTag nbttagcompound) {
+         // Paper end