Possible bug in [RelayCommand] async task

[DarthMazut]

Hello,
when I mark my command with [RelayCommand] and use async Task signature then when synchronouse part of code throws exception this exception is swallow and another criptic exception is thrown instead. Let me give you an excample:

In my view I bind Button's command to my VM command, like so:

<Button Command="{Binding CommandCommand}">Click Me</Button>

In my VM I do the following:

[RelayCommand]
 private async Task Command()
 {
      throw new NotImplementedException();
      await Task.Delay(100);
 }

this simulates any method that has some async call, but before awaiting it, an exception has been thrown by prior part of code.
In such case, after pressing button I receive:
Unhandled exception at 0x76B757B1 (combase.dll) in TestApp1.exe: 0xC000027B: Wystąpił wewnętrzny wyjątek aplikacji (parameters: 0x16B993B0, 0x00000001). and eventually this:
Exception thrown at 0x00DBE538 in TestApp1.exe: 0xC0000005: Access violation executing location 0x00DBE538.

This happens only when my method signature is async Task, when changing it to async void the proper exception is thrown.
My question is whether this is expected or it's a bug? Should I use async void? I though async Task is recommended?

This is obviously problematic because if I throw meaningfull exception from my code I'd like to see those instead of this Access violation internal stuff.