Fix zlib crashes on Node 24: use sync zlib to catch all errors

Node 24's stricter zlib can throw asynchronously via the internal
Zlib C++ binding's onerror callback, bypassing try/catch around the
async zlib.unzip()/zlib.deflate() calls. These become uncaught
exceptions that crash the process.

Fix: switch to zlib.unzipSync/deflateSync wrapped in try/catch.
Synchronous calls ensure all errors are catchable. The Transform
stream's _transform callback handles backpressure, so sync zlib
inside _transform is safe and doesn't block the event loop
(each call processes one packet, not large data).

Also wrap gunzipSync in minecraft.js for NBT parsing.
Also suppress compressor/decompressor errors during client shutdown.

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

Author: rom1504

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()
+      }
     }
   }
 }