Closes the underlying process and stops accumulating output.
Stops tracking the running process without closing it, so another owner (a
background task queue, say) can take it over: register your own stream()
callback and then()/catch() on the returned process. The hook will no longer
update its state for it, nor close it on unmount.
pending is output received after the last newline, which has not reached
lines yet — prepend it to the new owner's buffer so no output is lost.
Returns null when there is nothing to hand over: the process has not been
launched yet, or has already finished, or was cancelled or detached before.
true once the process exits (success or failure).
Error message when failed is true, otherwise empty string.
true when the process exited with an error.
All output lines received so far, with blank lines and CR stripped.
Accumulated result of a streaming Cockpit process.