tty: throw an Error when getWindowSize() fails

lib/tty.js

@@ -84,8 +84,10 @@ function WriteStream(fd) {
   this.writable = true;
 
   var winSize = this._handle.getWindowSize();
+  if (winSize) {
     this.columns = winSize[0];
     this.rows = winSize[1];
+  }
 }
 inherits(WriteStream, net.Socket);
 exports.WriteStream = WriteStream;
@@ -98,6 +100,9 @@ WriteStream.prototype._refreshSize = function() {
   var oldCols = this.columns;
   var oldRows = this.rows;
   var winSize = this._handle.getWindowSize();
+  if (!winSize) {
+    throw errnoException(errno, 'getWindowSize');
+  }
   var newCols = winSize[0];
   var newRows = winSize[1];
   if (oldCols !== newCols || oldRows !== newRows) {
@@ -124,3 +129,12 @@ WriteStream.prototype.clearScreenDown = function() {
 WriteStream.prototype.getWindowSize = function() {
   return [this.columns, this.rows];
 };
+
+
+// TODO share with net_uv and others
+function errnoException(errorno, syscall) {
+  var e = new Error(syscall + ' ' + errorno);
+  e.errno = e.code = errorno;
+  e.syscall = syscall;
+  return e;
+}