Stop on error

[hamogu]

When a script (e.g. a CIAO tool) reports an error, processing should be stopped to help debugging. Currently, it just pastes the next command which may run, take a long time, produce a lot of output and hid the actual error in the logs.
Not sure how to do that best, maybe some form of subprocess.check_output? But how would that work when multiple CIAO commands are executed?