I've got Cannot call method 'clear' of null, when my store configured as
Code:
{
     autoDestroy: true, 
     buffered: true
}
Notice that Ext.data.Store has method
Code:
destroyStore: function() {
        this.callParent(arguments);

        if (this.buffered) {
            this.data.clear(); // this.data is null
        }
    },
And parent class Ext.data.AbstractStore set me.data to null
Code:
destroyStore: function() {
        var me = this;

        if (!me.isDestroyed) {
            if (me.storeId) {
                Ext.data.StoreManager.unregister(me);
            }
            me.clearData();
            me.data = me.tree = me.sorters = me.filters = me.groupers = null;
            if (me.reader) {
                me.reader.destroyReader();
            }
            me.proxy = me.reader = me.writer = null;
            me.clearListeners();
            me.isDestroyed = true;

            if (me.implicitModel) {
                Ext.destroy(me.model);
            } else {
                me.model = null;
            }
        }
    },