Triggered when an init function is being invoked, as a result of startInitFunctionOrder.
Several onDataFileEntry may be triggered after this. After the init function finishes invoking, initFunctionInvoked will be triggered.
This is the data
provided to the message event:
interface EventData {
eventName: 'initFunctionInvoking',
type: string,
name: string,
idx: number,
}