There's a few confusing things here. For one, just because the allocator gave you an AllocError, that doesn't mean your function has to return an AllocError: you can return whatever error type you choose. If you want to collect a stack trace at that point, put one in there.

What value would a stack trace that includes internal allocator functions be to you? What do you lose by having to collect the stack trace at the point where your function receives an AllocError?