feature request: "prettier" error message for missing keys or empty YAML file

[wihobbs]

Hi folx! I was working with some new-to-HPC users in a tutorial this morning, and one of them observed that when a blank YAML or YAML missing values was passed to maestro run, you get an entire Python traceback:

(maestro_venv)   ruby968 /usr/global/docs/training/janeh $ maestro run ~/hostname.yaml
[2024-06-04 10:08:54: INFO] INFO Logging Level -- Enabled
[2024-06-04 10:08:54: WARNING] WARNING Logging Level -- Enabled
[2024-06-04 10:08:54: CRITICAL] CRITICAL Logging Level -- Enabled
[2024-06-04 10:08:54: INFO] Loading specification -- path = /g/g0/hobbs17/hostname.yaml
[2024-06-04 10:08:54: ERROR] ("'NoneType' object is not subscriptable",)
Traceback (most recent call last):
  File "/usr/global/docs/training/janeh/maestro_venv/lib/python3.10/site-packages/maestrowf/specification/yamlspecification.py", line 105, in load_specification
    specification = cls.load_specification_from_stream(data)
  File "/usr/global/docs/training/janeh/maestro_venv/lib/python3.10/site-packages/maestrowf/specification/yamlspecification.py", line 135, in load_specification_from_stream
    logger.debug("Loaded specification -- \n%s", spec["description"])
TypeError: 'NoneType' object is not subscriptable
Traceback (most recent call last):
  File "/usr/global/docs/training/janeh/maestro_venv/bin/maestro", line 8, in <module>
    sys.exit(main())
  File "/usr/global/docs/training/janeh/maestro_venv/lib/python3.10/site-packages/maestrowf/maestro.py", line 507, in main
    rc = args.func(args)
  File "/usr/global/docs/training/janeh/maestro_venv/lib/python3.10/site-packages/maestrowf/maestro.py", line 196, in run_study
    spec = YAMLSpecification.load_specification(args.specification)
  File "/usr/global/docs/training/janeh/maestro_venv/lib/python3.10/site-packages/maestrowf/specification/yamlspecification.py", line 109, in load_specification
    raise e
  File "/usr/global/docs/training/janeh/maestro_venv/lib/python3.10/site-packages/maestrowf/specification/yamlspecification.py", line 105, in load_specification
    specification = cls.load_specification_from_stream(data)
  File "/usr/global/docs/training/janeh/maestro_venv/lib/python3.10/site-packages/maestrowf/specification/yamlspecification.py", line 135, in load_specification_from_stream
    logger.debug("Loaded specification -- \n%s", spec["description"])
TypeError: 'NoneType' object is not subscriptable

It'd be great if this error were a little more condensed/descriptive of the problem: a missing "description" key in the YAML file (because the whole file is blank). Sorry to nit -- it just seems like this would be a fairly easy thing and helpful to newer users.

[jwhite242]

Oof, that is indeed an unhelpful output. I can certainly look into making that a little more human readable.