Currently observewatchstream!signal! don't fail when cancelled before termination. This is inconsistent and sometimes problematic :
if a transfer is pending and for some reason the value must not be propagated to the rest of the pipeline, there's no way to prevent that. If instead the flow fails on cancellation, then it can cancel pending transfers and short-circuit the pipeline.
no way to disambiguate between clean termination and abrupt termination (arguably less of a problem for observe and watch because they don't self-terminate, but they may be able to do so at some point - #6).
Currently
observe
watch
stream!
signal!
don't fail when cancelled before termination. This is inconsistent and sometimes problematic :observe
andwatch
because they don't self-terminate, but they may be able to do so at some point - #6).