How can I catch an exception that occurs in Tasks when using Task.WhenAll()?

Question

I tried putting the try catch around the Task.WhenAll(tasks) but it did not catch anything. In one of my tasks I tried to artificially generate an exception by using Substring on an empty string. But all that happens is the app crashes and defaults to Application_UnhandledException.

    private async void RunTasks()
    {

        tasks[0] = HttpExtensions.GetMyData("http://www....");

        tasks[1] = HttpExtensions.GetMyData("http://www.....");

        tasks[2] = GeoLocate.OneShotGeoLocate();

        try
        {
            await Task.WhenAll(tasks);
        }
        catch (AggregateException ae)
        {

            App.ViewModel.ErrorMessage = ae.Message;

        }

 }

Answer 1

This worked thanks to 'nakiya'

private async void RunTasks()
{

    tasks[0] = HttpExtensions.GetMyData("http://www....");

    tasks[1] = HttpExtensions.GetMyData("http://www.....");

    tasks[2] = GeoLocate.OneShotGeoLocate();

    try
    {
        await Task.WhenAll(tasks);
    }
    catch (Exception ae)
    {

        App.ViewModel.ErrorMessage = ae.Message;

    }

}