zlib: fix assert fail for bad write in object mode

lib/zlib.js

@@ -152,7 +152,6 @@ function flushCallback(level, strategy, callback) {
 // true or false if there is anything in the queue when
 // you call the .write() method.
 function Zlib(opts, mode) {
-  Transform.call(this, opts);
   var chunkSize = Z_DEFAULT_CHUNK;
   var flush = Z_NO_FLUSH;
   var finishFlush = Z_FINISH;
@@ -257,6 +256,7 @@ function Zlib(opts, mode) {
       opts.writableObjectMode = false;
     }
   }
+  Transform.call(this, opts);
   this.bytesRead = 0;
   this._handle = new binding.Zlib(mode);
   this._handle.jsref = this; // Used by processCallback() and zlibOnError()

test/parallel/test-zlib-object-write.js

@@ -0,0 +1,11 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const { Gunzip } = require('zlib');
+
+const gunzip = new Gunzip({ objectMode: true });
+assert.throws(
+  () => gunzip.write({}),
+  TypeError
+);