net.js: Check that readWatcher exists before pause, resume

lib/net.js

@@ -695,15 +695,17 @@ Stream.prototype.setTimeout = function(msecs) {
 
 
 Stream.prototype.pause = function() {
-  this._readWatcher.stop();
+  if (this._readWatcher) this._readWatcher.stop();
 };
 
 
 Stream.prototype.resume = function() {
   if (this.fd === null) throw new Error('Cannot resume() closed Stream.');
-  this._readWatcher.stop();
+  if (this._readWatcher) {
-  this._readWatcher.set(this.fd, true, false);
+    this._readWatcher.stop();
-  this._readWatcher.start();
+    this._readWatcher.set(this.fd, true, false);
+    this._readWatcher.start();
+  }
 };
 
 Stream.prototype.destroySoon = function() {