silent die on incorrect node selection

[lennybe]

In the scenario below, ci-demo is not executing step, since nodeLabel does not exist in run_on_agents,
But there is no error, so job exits with success

http://hpc-master.lab.mtl.com:8080/view/UFM/job/UFM-CI/728/console

runs_on_agents:

• nodeLabel: 'UFM-POC'

name: Install UFM
agentSelector: "{nodeLabel: 'UFM-CI'}"
run: |
echo "Uninstalling UFM on $name"