[Condition Sets] Breaking when no telemetry is returned

[jvigliotta]

Summary

If no telemetry is ever returned to a condition set, it will throw errors. This was causing the Default Display in openmct-yamcs examples to break if the user forgot to run the simulator. akhenry/openmct-yamcs#490 (comment)

Expected vs Current Behavior

Steps to Reproduce

1. Follow the steps on https://github.com/akhenry/openmct-yamcs to get up and running with quickstart (must be a fresh version, remove any existing openmct-yamcs repo)
2. Do not run the simulator simulator.py
3. View the example at localhost:9000
4. Screen covering errors... many of them

Impact Check List

• Data loss or misrepresented data?
• Regression? Did this used to work or has it always been broken?
• Is there a workaround available?
• Does this impact a critical component?
• Is this just a visual bug with no functional impact?
• Does this block the execution of e2e tests?
• Does this have an impact on Performance?

Additional Information

[jvigliotta]

Testing

• above repro steps