I am using ExtJS 4.1.0. and I am testing out in Firefox 13.0.1

I have a float field set up in one of my models defined as such:

 {name: 'statValueNumber', type: 'float', useNull: true}
I specified the useNull config so null values would not show up as 0.

Inside a gridPanel, I show the value of this field in this manner:

initComponent: function() {
         Ext.apply(this, {
            columns: {
                items: [
                      {header: 'STAT_VALUE_N', dataIndex: 'statValueNumber', flex: 3, editor: 'numberfield', hideable: false},
The grid panel is being populated via data from my server using a store that accepts json formatted data. In some cases this particular field above is null.

Ever since I set the useNull config to true, I am receiving the following repeating error in firefox's firebug:

An invalid or illegal string was specified

The same code in IE does not throw an error.

This seems to just be a nuisance but I'd rather not see it continuously pop up. I dont believe anything is configured incorrectly, I'd just rather not see a value in my panel rather than the default of 0 if this field is null. I could also configure this field to be a String instead, but I'd rather not do this.

Please let me know your thoughts on this error I am getting from firebug