Hot module reloading throws if subGridConfigs is used

[bmblb]

Reproducible in grid basic demo, just call grid.subGridConfigs = { normal : {} }. This is what gets called in framework demos when re-rendering components

[bmblb]

More problems occur when you try to apply this config twice to the scheduler pro:

const config = {
    infiniteScroll : true,

    timeAxis : {
        listeners : {}
    },

    viewPreset : {
        base           : 'dayAndWeek',
        tickWidth      : 50,
        timeResolution : {
            unit      : 'day',
            increment : 1
        },
        headers : [
            {
                unit       : 'day',
                dateFormat : 'ddd DD'
            }
        ]
    }
};