If a channel is already closed it will receive no new frames and waiting
for confirmations will most likely hang and timeout unless the frames
were somehow already received.
If one wishes to wait for confirmations it’s probably the case that the
user doesn’t expect the channel to be closed and we should notify them
about it by failing early. A channel might be closed by RabbitMQ in case
of a channel-level error for example due to a publishing error.