为什么关闭 SubscriptionClient 实例会导致 CanceledException？

如何解决为什么关闭 SubscriptionClient 实例会导致 CanceledException？

关闭 SubscriptionClient 实例会立即导致 CanceledException。

客户：

Xamarin.Forms

设置：

subscriptionClient <- new SubscriptionClient(connectionString,topic,subscription)
subscriptionClient.OperationTimeout <- TimeSpan.FromMinutes(5.0)

let msgOptions = MessageHandlerOptions(fun args -> exceptionReceivedHandler(args))
msgOptions.AutoComplete         <- false
msgOptions.MaxAutoRenewDuration <- TimeSpan.FromHours(1.0)
msgOptions.MaxConcurrentCalls   <- 1

subscriptionClient.RegisterMessageHandler(processMessageAsync,msgOptions)

执行

if not (subscriptionClient.IsClosedOrClosing) then
    do! subscriptionClient.CloseAsync() |> Async.AwaitTask // THROWS EXCEPTION

预期：

No exception

实际：

System.OperationCanceledException: 'The operation was canceled.'