ThouShaltNotPassCancellationTokenToTaskValuedContinuations

Fixing an issue where the continuation that is used to observe exceptions inside the receive loop in the websocket transport would be cancelled because it took a cancellation token that had been cancelled because the transport is being disconnected. If in this state the receive task had thrown an exception (which is pretty much guaranteed because when disconnecting the websocket is closed when the receive task is still pending) we would not have observe the exception. This unobserved exception would crash the process. The fix is to separate the continuation into two - one that is value based, takes the cancellation token, reads the message content and schedules the next iteration and one that is task based and does not take a cancellation token. The first one may not run in case of exceptions or when the cancellation token is set to cancelled while the second one is guaranteed to run in case of exceptions or cancellation.
There is no way to observe this exception from the test.
TL;DR;
The exception happens on a different thread that we don't have access - this is the receive loop which is unsynchronized. The only place to observe the exception is within the receive loop itself. Casablanca is controlling the task so they internally know if the exception was observed or not and if it was not they will rethrow causing a crash.