whonixcheck:
whonix_shared/etc/init.d/whonixcheckd: on stop, give whonixcheck time to gracefully shut down so it can close any still eventually open progress bars
whonix_shared/usr/lib/whonix/process_killer_helper: implement error_handler if there is none already
whonix_shared/usr/lib/whonix/whonixcheck/75_cleanup: fix, also close "waiting for package manager" waiting progress bar, it whonixcheck gets shut down by its init script