Invalid memory operation during allocation with `new`

[Per Nordlöw]

On Sunday, 12 January 2020 at 17:36:23 UTC, Adam D. Ruppe wrote:
> Of course that doesn't help the case when you don't know the 
> rule and don't even think to call it.......

Thanks. I checked and @nogc-qualified all the class destructors 
defined in my project. Without finding any potential problems. 
Any other suggestions on how to trace this problem?