set_error |
This optional method is called if either on calling await
or yield
on the upstream process an exception was thrown. The pointer of the caught exception is passed. In case that the process does not provide this method, close
is called instead of. So a process should try to handle its errors within itself. Only errors which occur while passing arguments to the process or retrieving from the process are caught here and then passed to the next downstream process, because this process is not able to handle them.