筛选速度过快

In ExtJS 4.1.3 we have a filter setup on a text field to run 'onchange' of the text field. This is the function onchange:

var store = this.getStore();
value = field.getValue();

if (value.length > 0) {
    // Param name is ignored here since we use custom encoding in the proxy.
    // id is used by the Store to replace any previous filter
    store.filter({
        id: 'query',
        property: 'query',
        value: 'LegalName|#|#|' + value
    });

} else {
    store.clearFilter();
}

Now, we are running into an issue where when I type something in the text field too fast I am getting errors and am getting stuck on a load screen. When I type in the same thing slowly it works. Considering typing it in slowly makes it work, but fast makes it fail and the data coming back from the server is the same in both instances, I'm assuming it's an issue with ExtJS. Has anyone seen an issue like this? What are potential problems and fixes. I can't figure out why it's breaking. Here is the trail I get:

Uncaught TypeError: Cannot convert null to object ext-all-debug.js:51752
    Ext.define.cancelAllPrefetches ext-all-debug.js:51752
    Ext.util.Event.Ext.extend.fire ext-all-debug.js:8638
    Ext.define.continueFireEvent ext-all-debug.js:25117
    Ext.define.fireEvent ext-all-debug.js:25095
    Ext.define.clear ext-all-debug.js:44718
    Base.implement.callParent ext-all-debug.js:3735
    Ext.define.clear ext-all-debug.js:47485
    Base.implement.callParent ext-all-debug.js:3735
    PageMap.Ext.Class.clear ext-all-debug.js:52358
    Ext.define.filter ext-all-debug.js:51377
    Ext.define.onTextfieldChange /TEST/app/view/ContractGrid.js?_dc=1354553533935:447
    Ext.util.Event.Ext.extend.fire ext-all-debug.js:8638
    Ext.define.continueFireEvent ext-all-debug.js:25117
    Ext.define.fireEvent ext-all-debug.js:25095
    Ext.override.fireEvent ext-all-debug.js:58382
    Ext.define.checkChange ext-all-debug.js:30310
    call ext-all-debug.js:8426

Any thoughts?

I was able to fix the issue by changing the buffer setting on the store. Looks like I had set 'buffered' to true in the store and once I removed it, the issue went away.