Windows: picker updating data throws unknown exception

function onTest() {

	var column = picker.columns[0];

	_.each(column.rows, function(row) {

		column.removeRow(row);

	});

	var data = [];

	data[0]=Ti.UI.createPickerRow({title:'2 Bananas'});

	data[1]=Ti.UI.createPickerRow({title:'2 Strawberries'});

	data[2]=Ti.UI.createPickerRow({title:'2 Mangos'});

	data[3]=Ti.UI.createPickerRow({title:'2 Grapes'});

	picker.add(data);

}

//----------------------------

var picker = Ti.UI.createPicker({

  top:50

});

var data = [];

data[0]=Ti.UI.createPickerRow({title:'Bananas'});

data[1]=Ti.UI.createPickerRow({title:'Strawberries'});

data[2]=Ti.UI.createPickerRow({title:'Mangos'});

data[3]=Ti.UI.createPickerRow({title:'Grapes'});

picker.add(data);

$.win.add(picker);

$.win.open();

_.delay(onTest, 2000);