Fix C2ME reintroducing MC-263340

[DrexHD]

Message copied from the discord server:

I am pretty sure C2ME re-introduces this bug: https://bugs.mojang.com/browse/MC-263340 in C2MEs MixinChunkStatus, which is mostly a VanillaCopy. I have noticed this, because I got some Failed to save chunk {},{} asynchronously, falling back to sync saving when updating and testing C2ME on 24w04a with fabric api, because Fabric API uses the chunk type here to check if a chunk is a LevelChunk, which caused a ClassCastException, because the chunk was a ProtoChunk and not LevelChunk, which implements that interface. I am not really sure why I only encountered this bug now, because I don't see a reason why it would be different in 24w04a than 1.20.4!

(attached is Mojangs fix for the bug, in mojmap)
When applying the same change Mojang made to C2MEs mixin this doesn't seem to happen anymore.

diff --git a/minecraft/src/net/minecraft/world/level/chunk/ChunkStatus.java b/minecraft/src/net/minecraft/world/level/chunk/ChunkStatus.java
index da3b216..e7dbfda 100755
--- a/minecraft/src/net/minecraft/world/level/chunk/ChunkStatus.java
+++ b/minecraft/src/net/minecraft/world/level/chunk/ChunkStatus.java
@@ -380,10 +380,11 @@ public class ChunkStatus {
 		return this.generationTask
 			.doWork(this, executor, serverLevel, chunkGenerator, structureTemplateManager, threadedLevelLightEngine, function, list, chunkAccess)
 			.thenApply(either -> {
-				if (chunkAccess instanceof ProtoChunk protoChunk && !protoChunk.getStatus().isOrAfter(this)) {
-					protoChunk.setStatus(this);
-				}
-	
+				either.ifLeft(chunkAccessx -> {
+					if (chunkAccessx instanceof ProtoChunk protoChunk && !protoChunk.getStatus().isOrAfter(this)) {
+						protoChunk.setStatus(this);
+					}
+				});
 				if (profiledDuration != null) {
 					profiledDuration.finish();
 				}