`lazyLoad` with TreeGrid hangs

[ExtAnimal]

Forum post

This is because the store's lazyLoad property is being accessed before the plugin instance is assigned to the lazyLoad property.

treeStoreLazyLoadPlugin#doLazyLoad needs a .catch(error => {... me.trigger('exception'...) }) which would have caught this.

The plugin itself need to inject itself into its client store as lazyLoad during its startup.