Fix zlib crashes on Node 24: use sync zlib everywhere

Async zlib (deflate, unzip, gunzip) creates internal Zlib C++ handles
that can fire onerror asynchronously, becoming uncaught exceptions on
Node 24. Sync versions (deflateSync, unzipSync) complete immediately
with no lingering handles. Each call processes one small packet, so
sync is safe in the Transform._transform context.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: rom1504

package.json

@@ -58,7 +58,7 @@
     "node-rsa": "^0.4.2",
     "prismarine-auth": "^2.2.0",
     "prismarine-chat": "^1.10.0",
-    "prismarine-nbt": "^2.5.0",
+    "prismarine-nbt": "PrismarineJS/prismarine-nbt#fix-zlib-node24",
     "prismarine-realms": "^1.2.0",
     "protodef": "^1.17.0",
     "readable-stream": "^4.1.0",

src/client.js

@@ -224,11 +224,15 @@ class Client extends EventEmitter {
   setCompressionThreshold (threshold) {
     if (this.compressor == null) {
       this.compressor = compression.createCompressor(threshold)
-      this.compressor.on('error', (err) => this.emit('error', err))
+      this.compressor.on('error', (err) => {
+        if (!this.ended) this.emit('error', err)
+      })
       this.serializer.unpipe(this.framer)
       this.serializer.pipe(this.compressor).pipe(this.framer)
       this.decompressor = compression.createDecompressor(threshold, this.hideErrors)
-      this.decompressor.on('error', (err) => this.emit('error', err))
+      this.decompressor.on('error', (err) => {
+        if (!this.ended) this.emit('error', err)
+      })
       this.splitter.unpipe(this.deserializer)
       this.splitter.pipe(this.decompressor).pipe(this.deserializer)
     } else {

src/datatypes/minecraft.js

@@ -56,7 +56,12 @@ function readCompressedNbt (buffer, offset) {
 
   const compressedNbt = buffer.slice(offset + 2, offset + 2 + length)
 
-  const nbtBuffer = zlib.gunzipSync(compressedNbt) // TODO: async
+  let nbtBuffer
+  try {
+    nbtBuffer = zlib.gunzipSync(compressedNbt) // TODO: async
+  } catch (err) {
+    throw new PartialReadError('zlib decompress failed: ' + err.message)
+  }
 
   const results = nbt.proto.read(nbtBuffer, 0, 'nbt')
   return {

src/transforms/compression.js

@@ -20,14 +20,16 @@ class Compressor extends Transform {
 
   _transform (chunk, enc, cb) {
     if (chunk.length >= this.compressionThreshold) {
-      zlib.deflate(chunk, (err, newChunk) => {
-        if (err) { return cb(err) }
+      try {
+        const newChunk = zlib.deflateSync(chunk)
         const buf = Buffer.alloc(sizeOfVarInt(chunk.length) + newChunk.length)
         const offset = writeVarInt(chunk.length, buf, 0)
         newChunk.copy(buf, offset)
         this.push(buf)
         return cb()
-      })
+      } catch (err) {
+        return cb(err)
+      }
     } else {
       const buf = Buffer.alloc(sizeOfVarInt(0) + chunk.length)
       const offset = writeVarInt(0, buf, 0)
@@ -52,23 +54,23 @@ class Decompressor extends Transform {
       this.push(chunk.slice(size))
       return cb()
     } else {
-      zlib.unzip(chunk.slice(size), { finishFlush: 2 /*  Z_SYNC_FLUSH = 2, but when using Browserify/Webpack it doesn't exist */ }, (err, newBuf) => { /** Fix by lefela4. */
-        if (err) {
-          if (!this.hideErrors) {
-            console.error('problem inflating chunk')
-            console.error('uncompressed length ' + value)
-            console.error('compressed length ' + chunk.length)
-            console.error('hex ' + chunk.toString('hex'))
-            console.log(err)
-          }
-          return cb()
-        }
+      try {
+        const newBuf = zlib.unzipSync(chunk.slice(size), { finishFlush: 2 })
         if (newBuf.length !== value && !this.hideErrors) {
           console.error('uncompressed length should be ' + value + ' but is ' + newBuf.length)
         }
         this.push(newBuf)
         return cb()
-      })
+      } catch (err) {
+        if (!this.hideErrors) {
+          console.error('problem inflating chunk')
+          console.error('uncompressed length ' + value)
+          console.error('compressed length ' + chunk.length)
+          console.error('hex ' + chunk.toString('hex'))
+          console.log(err)
+        }
+        return cb()
+      }
     }
   }
 }