crash when calling req.closeWait()
Hi,
please forgive me if i misunderstood something really basic that makes this issue;
i am trying to do a simple get request and the application is crashing
```
proc getipv4*(): string =
    var session = createSession(true)
    # let address = initTAddress("api.ipify.org:443")
    let address = resolveTAddress("api.ipify.org",443.Port,Domain.AF_INET)[0]
    let ha = getAddress(address, HttpClientScheme.Secure, "/")
    var req = HttpClientRequestRef.new(session, ha, MethodGet)
    let response = waitFor fetch(req)
    if response.status == 200:
        let data = cast[string](response.data)
        result = data
    else:
        result = "fail"

    waitFor(req.closeWait()) #crash happens at this line with msg  'Future operation cancelled!'
    waitFor(session.closeWait())
```
log:
>terminate called without an active exception
>Traceback (most recent call last)
>C:\\....\server.nim(68) server
>C:\\...\nettools.nim(35) getipv4
>C:\\....\nimble\pkgs\chronos-3.0.11\chronos\asyncloop.nim(1203) waitFor
>C:\\....\nimble\pkgs\chronos-3.0.11\chronos\asyncloop.nim(295) poll
>C:\\....\nimble\pkgs\chronos-3.0.11\chronos\asyncsync.nim(372) popFirst
>SIGABRT: Abnormal termination.

