zlib: remove redundant variable in zlibBufferOnEnd

PR-URL: #34072
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

lib/zlib.js

@@ -138,17 +138,14 @@ function zlibBufferOnError(err) {
 
 function zlibBufferOnEnd() {
   let buf;
-  let err;
   if (this.nread === 0) {
     buf = Buffer.alloc(0);
   } else {
     const bufs = this.buffers;
     buf = (bufs.length === 1 ? bufs[0] : Buffer.concat(bufs, this.nread));
   }
   this.close();
-  if (err)
-    this.cb(err);
-  else if (this._info)
+  if (this._info)
     this.cb(null, { buffer: buf, engine: this });
   else
     this.cb(null, buf);