How to reproduce:
Select a cell in the last row of a grid using cell selection model and remove any record from the grid's store. The following error occurs:
Code:
Uncaught TypeError: Cannot read property 'id' of undefined
Ext.define.getKey
Ext.define.add
Ext.define.doMultiSelect
Ext.define.doSelect
Ext.define.onCellSelect  
Ext.define.refresh
Ext.define.refresh
Base.callParent
Ext.define.refresh
Base.callParent
Ext.define.refresh
Base.callParent
Ext.define.refresh
Ext.define.onDataChanged
fire
Ext.define.fireEvent
Ext.define.remove
Ext.define.removeAt