Silent error when using hashmap

[FatalCatharsis via Digitalmars-d]

On Wednesday, 26 July 2017 at 16:39:15 UTC, ketmar wrote:>
> 'cause `WM_CREATE` is not the first message window receiving. 
> check if hwnd is in hash with `in` first.

I figured this was the case. WM_NCCREATE is probably sent first 
and the lookup fails. I'm more concerned with why there was no 
exceptions/debug output of any kind.

On Wednesday, 26 July 2017 at 22:08:45 UTC, Steven Schveighoffer 
wrote:
> Note that in D when a thread crashes besides the main thread, 
> you may not get a stack trace printout. You may get nothing.
>
> -Steve

This example doesn't create any threads explicitly. Are there 
other threads that dlang generates? How do I obtain debug output 
and proper exception handling from these threads?