Grid.hideHeader bug

hideHeaders causes "Layout run failed" with 4.2.1 (not 4.2.0!)

HTML

<script src="http://cdn.sencha.com/ext/gpl/4.2.1/ext-all-dev.js"></script>

CSS

@import 'http://cdn.sencha.io/ext/gpl/4.2.1/resources/ext-theme-neptune/ext-theme-neptune-all.css'

JavaScript

var DATA = [
    ['S', 'Shares total', 139122.83, 13874.98],
    ['CB', 'Cash Balance', 74847.33, 1069.32],
    ['P', 'Portfolio', 213970.16, 14944.3],
    ['B', 'Benchmark', 219206.95, 20181.09]
];

Ext.define('PerformanceGridModel', {
    extend: 'Ext.data.Model',

    fields: [
        { name: 'ShareCode', type: 'string', useNull: true },
        { name: 'ShareName', type: 'string', useNull: true },
        { name: 'ValueHeld_End', type: 'number', useNull: true },
        { name: 'TotalPnL', type: 'number', useNull: true },
    ]
});

Ext.onReady(function () {
    var store = Ext.create('Ext.data.ArrayStore', {
        model: 'PerformanceGridModel',
        data: DATA,
        autoLoad: true
    });

    Ext.create('Ext.grid.Panel', {
        renderTo: Ext.getBody(),
        width: 800,
        height: 600,

        title: 'Performance',
        store: store,
      

        viewConfig: {
            stripeRows: true
        },

        columns: [{
            text: 'Code',
            width: 60,
            dataIndex: 'ShareCode'
        }, {
            text: 'Share',
            width: 100,
            dataIndex: 'ShareName'
        }, {
            text: 'Close',
            columns: [{
                text: 'Value',
                width: 90,
                dataIndex: 'ValueHeld_End'
            }, {
                text: 'Total Profit/(loss)',
                width: 120,
                dataIndex: 'TotalPnL'
            }]
        }]
    });
});