From 4dbeed933b212a6b1f3b078979cede8944c6841a Mon Sep 17 00:00:00 2001
From: LJ <23249107+LJNeon@users.noreply.github.com>
Date: Wed, 2 Jul 2025 16:18:11 -0700
Subject: [PATCH] chore(WebSocketShard): improve zlib-sync errors (#10808)

* chore(WebSocketShard): improve zlib-sync errors

* chore(WebSocketShard): move zlib-sync error numbers to constants file

* chore(WebSocketShard): move enum, zlib-sync is lazily loaded

---------

Co-authored-by: Almeida <github@almeidx.dev>
---
 packages/ws/src/ws/WebSocketShard.ts | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/packages/ws/src/ws/WebSocketShard.ts b/packages/ws/src/ws/WebSocketShard.ts
index 360e97413..ec786be29 100644
--- a/packages/ws/src/ws/WebSocketShard.ts
+++ b/packages/ws/src/ws/WebSocketShard.ts
@@ -668,10 +668,23 @@ export class WebSocketShard extends AsyncEventEmitter<WebSocketShardEventsMap> {
 				this.zLibSyncInflate.push(Buffer.from(decompressable), flush ? zLibSync.Z_SYNC_FLUSH : zLibSync.Z_NO_FLUSH);
 
 				if (this.zLibSyncInflate.err) {
-					this.emit(
-						WebSocketShardEvents.Error,
-						new Error(`${this.zLibSyncInflate.err}${this.zLibSyncInflate.msg ? `: ${this.zLibSyncInflate.msg}` : ''}`),
-					);
+					// Must be here because zlib-sync is lazily loaded
+					const ZlibErrorCodes = {
+						[zLibSync.Z_NEED_DICT]: 'Z_NEED_DICT',
+						[zLibSync.Z_STREAM_END]: 'Z_STREAM_END',
+						[zLibSync.Z_ERRNO]: 'Z_ERRNO',
+						[zLibSync.Z_STREAM_ERROR]: 'Z_STREAM_ERROR',
+						[zLibSync.Z_DATA_ERROR]: 'Z_DATA_ERROR',
+						[zLibSync.Z_MEM_ERROR]: 'Z_MEM_ERROR',
+						[zLibSync.Z_BUF_ERROR]: 'Z_BUF_ERROR',
+						[zLibSync.Z_VERSION_ERROR]: 'Z_VERSION_ERROR',
+					} as const satisfies Record<number, string>;
+
+					// Try to match nodejs zlib errors as much as possible
+					const error: NodeJS.ErrnoException = new Error(this.zLibSyncInflate.msg ?? undefined);
+					error.errno = this.zLibSyncInflate.err;
+					error.code = ZlibErrorCodes[this.zLibSyncInflate.err];
+					this.emit(WebSocketShardEvents.Error, error);
 				}
 
 				if (!flush) {